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#include <bits/stdc++.h> using namespace std; const double pi = acos(-1.0); const int INF = 0x3f3f3f3f; const int MOD = 1e9 + 7; const double EPS = 1e-9; int getint() { int x = 0; char c = getchar(); while (c != '-' && c != '+' && !isdigit(c)) c = getchar(); int flag = '-' == c ? -1 : 1; while (isdigit(c)) { x = x * 10 + c - '0'; c = getchar(); } return flag * x; } void putint(int x) { char s[15]; if (x < 0) putchar('-'), x = -x; int l = 0; if (!x) putchar('0'); while (x) s[++l] = x % 10 + '0', x /= 10; while (l) putchar(s[l--]); } int n, l[105], r[105], vis[105]; vector<pair<int, int> > ans; int main() { scanf("%d", &n); for (int i = 1; i <= n; ++i) { scanf("%d%d", &l[i], &r[i]); } for (int i = 1; i <= n; ++i) { if (vis[i]) continue; int j = i, k = i; vis[i] = 1; while (l[j]) j = l[j], vis[j] = 1; while (r[k]) k = r[k], vis[k] = 1; ans.push_back(make_pair(j, k)); } int cur_e = ans[0].second; for (int i = 1; i < ans.size(); ++i) { int s = ans[i].first, e = ans[i].second; r[cur_e] = s, l[s] = cur_e, cur_e = e; } for (int i = 1; i <= n; ++i) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int N = 500001; int n, l[N], r[N], dsu[N]; int find(int u) { return dsu[u] == u ? u : dsu[u] = find(dsu[u]); } int main() { cin >> n; for (int i = 1; i <= n; ++i) dsu[i] = i; for (int i = 1; i <= n; ++i) { cin >> l[i] >> r[i]; if (l[i]) dsu[find(i)] = find(l[i]); if (r[i]) dsu[find(i)] = find(r[i]); } for (int i = 1; i <= 2 * n; ++i) { for (int j = 1; j <= n; ++j) { for (int k = 1; k <= n; ++k) { if (k == j) continue; if (r[j] == 0 && l[k] == 0 && find(j) != find(k)) { l[k] = j; r[j] = k; dsu[find(k)] = find(j); } } } } for (int i = 1; i <= n; ++i) { printf("%d %d\n", l[i], r[i]); } return 0; }
#include <bits/stdc++.h> using namespace std; int F[105], N[105], book[105], k; void Find(int x, int s) { if (N[x] == 0) { book[x] = s; return; } book[x] = s; Find(N[x], s); } int main() { int n, last1, Front, last2; k = 1; scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d%d", &F[i], &N[i]); for (int i = 1; i <= n; i++) if (F[i] == 0 && book[i] == 0) Find(i, k++); for (int i = 1; i <= n; i++) { if (N[i] == 0 && book[i] == 1) last1 = i; } last2 = last1; for (int i = 2; i < k; i++) { last1 = last2; for (int j = 1; j <= n; j++) { if (N[j] == 0 && book[j] == i) last2 = j; if (F[j] == 0 && book[j] == i) Front = j; } F[Front] = last1; N[last1] = Front; } for (int i = 1; i <= n; i++) printf("%d %d\n", F[i], N[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int maxn = 101; int a[maxn][2], parent[maxn]; int Find(int x) { if (x == parent[x]) return x; return Find(parent[x]); } void unite(int x, int y) { int xx = Find(x), yy = Find(y); if (xx == yy) return; parent[y] = x; } void init(int n) { for (int i = 1; i <= n; i++) parent[i] = i; } int main() { int n; while (scanf("%d", &n) == 1) { init(n); for (int i = 1; i <= n; i++) { scanf("%d%d", &a[i][0], &a[i][1]); if (a[i][0]) unite(a[i][0], i); if (a[i][1]) unite(i, a[i][1]); } for (int i = 1; i <= n; i++) { if (a[i][1] != 0) continue; for (int j = 1; j <= n; j++) { if (i == j) continue; if (a[j][0] != 0) continue; if (Find(i) == Find(j)) continue; a[i][1] = j; a[j][0] = i; unite(i, j); break; } } for (int i = 1; i <= n; i++) { printf("%d %d\n", a[i][0], a[i][1]); } } return 0; }
#include <bits/stdc++.h> using namespace std; pair<int, int> ar[110]; set<int> se; int findstart(int k) { while (ar[k].first != 0) k = ar[k].first; return k; } int findend(int k) { while (ar[k].second != 0) k = ar[k].second; return k; } void addalltoend(int i) { se.insert(ar[i].second); while (ar[i].second != 0) { i = ar[i].second; se.insert(ar[i].second); } } int main() { int n, en, nen; cin >> n; for (int i = 1; i <= n; i++) { cin >> ar[i].first >> ar[i].second; } int i = 0; while (ar[i].first == 0 && ar[i].second == 0 && i != n + 1) { i++; } if (n == 1) { cout << 0 << " " << 0; return 0; } if (n != 1 && i == n + 1) { for (i = 1; i < n; i++) { cout << i - 1 << ' ' << i + 1 << '\n'; } cout << i - 1 << ' ' << 0 << '\n'; return 0; } i = findstart(i); en = findend(i); se.insert(i); addalltoend(i); se.erase(0); for (set<int>::const_iterator it = se.begin(); it != se.end(); it++) for (int i = 1; i <= n; i++) { if (ar[i].first == 0 && ar[i].second != 0 && se.find(ar[i].second) == se.end()) { ar[en].second = i; ar[i].first = en; i = findstart(i); addalltoend(i); en = findend(i); } } for (int i = 1; i <= n; i++) { if (ar[i].first == 0 && ar[i].second == 0) { ar[en].second = i; ar[i].first = en; en = i; } } for (int i = 1; i <= n; i++) cout << ar[i].first << ' ' << ar[i].second << '\n'; for (set<int>::const_iterator it = se.begin(); it != se.end(); it++) return 0; }
#include <bits/stdc++.h> using namespace std; const int INF = 987654321; const long long MOD = 1e9 + 7; const int N = 2e5 + 100; int l[N], r[N]; vector<pair<int, int> > vec; int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; } for (int i = 1; i <= n; i++) { if (l[i] == 0) { int temp = i; while (r[temp] != 0) temp = r[temp]; vec.push_back(pair<int, int>(i, temp)); } } for (int i = 0; i < vec.size() - 1; i++) { int a = vec[i].second; int b = vec[i + 1].first; l[b] = a; r[a] = b; } for (int i = 1; i <= n; i++) cout << l[i] << " " << r[i] << endl; return 0; }
#include <bits/stdc++.h> using namespace std; template <class T> inline T sqr(T x) { return x * x; } const double EPS = 1e-6; const int INF = 0x3fffffff; const long long LINF = INF * 1ll * INF; const double PI = acos(-1.0); using namespace std; int l[105], r[105]; bool checkleft(int x, int y) { if (l[x] == 0) return true; else if (l[x] == y) return false; return checkleft(l[x], y); } bool checkright(int x, int y) { if (r[x] == 0) return true; else if (r[x] == y) return false; return checkleft(r[x], y); } int main() { int n; scanf("%d", &n); int cnt = 0; for (int i = 1; i <= n; i++) { scanf("%d%d", &l[i], &r[i]); if (l[i] == 0) cnt++; } for (int i = 1; i <= n; i++) { if (r[i] == 0 && cnt > 1) { for (int j = 1; j <= n; j++) { if (l[j] == 0 && i != j && checkleft(i, j) && checkright(i, j)) { cnt--; r[i] = j; l[j] = i; break; } } } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; set<int> lft; set<int> rt; int b4[105], af[105]; int main() { int n; cin >> n; vector<int> v; for (int i = 1; i <= n; i++) { cin >> b4[i] >> af[i]; if (!b4[i]) v.push_back(i); } int j = 0; for (int i = 0; i < v.size() - 1; i++) { for (j = v[i]; af[j]; j = af[j]) ; af[j] = v[i + 1]; b4[v[i + 1]] = j; } for (int i = 1; i <= n; i++) cout << b4[i] << ' ' << af[i] << '\n'; return 0; }
#include <bits/stdc++.h> using namespace std; const int MAX_N = 124; int l[MAX_N], r[MAX_N], used[124]; int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; if (l[i] != 0) r[l[i]] = i; if (r[i] != 0) l[r[i]] = i; } int curr; for (int i = 1; i <= n; i++) if (l[i] == 0) { curr = i; break; } for (int i = 1; i <= n; i++) { used[curr] = 1; if (r[curr] == 0) { for (int j = 1; j <= n; j++) { if (used[j] == 0 && l[j] == 0) { r[curr] = j, l[j] = curr, curr = j; break; } } } else curr = r[curr]; } for (int i = 1; i <= n; i++) cout << l[i] << " " << r[i] << endl; return 0; }
#include <bits/stdc++.h> using namespace std; const int INF = 0x3f3f3f3f; const int T = 105; bool vis[T]; int ant[T]; int nxt[T]; int dfs(int at) { while (!vis[nxt[at]]) { vis[at] = 1; if (nxt[at]) at = nxt[at]; else break; } return at; } int main() { ios_base::sync_with_stdio(false); int n; cin >> n; queue<int> lista; for (int i = 1; i <= n; i++) { cin >> ant[i] >> nxt[i]; if (!ant[i]) lista.push(i); } int last = 0; while (!lista.empty()) { int at = lista.front(); lista.pop(); vis[at] = 1; ant[at] = last; nxt[last] = at; last = dfs(at); } for (int i = 1; i <= n; i++) cout << ant[i] << " " << nxt[i] << '\n'; return 0; }
#include <bits/stdc++.h> using namespace std; int l[110]; int r[110]; vector<int> v[110]; int lef[110]; int righ[110]; int main() { int n; cin >> n; for (int i = 0; i < n; i++) { cin >> l[i] >> r[i]; v[i].push_back(0); } int br = 0; while (br < n) { int da = 0; for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { if (v[j][v[j].size() - 1] == l[i]) { v[j].push_back(i + 1); l[i] = -1; r[i] = -1; br++; da = 1; break; } } if (da == 1) { break; } } } for (int i = 0; i < n; i++) { for (int j = 0; j < v[i].size(); j++) { int koji = v[i][j]; lef[koji - 1] = v[i][j - 1]; if (j + 1 == v[i].size()) { if (v[i + 1].size() > 1) { righ[koji - 1] = v[i + 1][1]; } else { righ[koji - 1] = 0; } } else { righ[koji - 1] = v[i][j + 1]; } } } for (int i = 0; i < n; i++) { cout << lef[i] << " " << righ[i] << endl; } return 0; }
#include <bits/stdc++.h> const bool multitest = 0; using namespace std; using ll = long long; using pii = pair<int, int>; pii read_pii() { int a, b; cin >> a >> b; return {a, b}; } void solve() { int n; cin >> n; vector<pii> dt(n); for (auto &p : dt) p = read_pii(); bool f = true; for (int i = 0; i < n; i++) { if (dt[i].first == 0) { if (f) { f = false; continue; } for (int j = 0; j < n; j++) { bool f = false; int a = i; while (a >= 0) { if (a == j) { f = true; break; } a = dt[a].second - 1; } if (f) continue; if (dt[j].second == 0) { dt[j].second = i + 1; dt[i].first = j + 1; break; } } } } for (auto &p : dt) cout << p.first << ' ' << p.second << endl; } int main() { ios::sync_with_stdio(0); cout.tie(0); int t = 1; if (multitest) cin >> t; for (; t--;) { solve(); } }
#include <bits/stdc++.h> using namespace std; struct Node { int left, right, idx; } nodes[115]; int idsListas[115]; vector<Node> listas[115]; vector<int> graph[115]; bool vis[115]; void solve(int l1, int l2, int qtdListas) { if (qtdListas == 1) return; int l1conect, l2conect; for (int i = 0; i < ((int)listas[l1].size()); i++) { if (listas[l1][i].right == 0) { l1conect = i; break; } } for (int i = 0; i < ((int)listas[l2].size()); i++) { if (listas[l2][i].left == 0) { l2conect = i; break; } } int idx1, idx2; idx1 = listas[l1][l1conect].idx; idx2 = listas[l2][l2conect].idx; nodes[idx1].right = idx2; nodes[idx2].left = idx1; if (l2 == qtdListas - 1) return; solve(l1 + 1, l2 + 1, qtdListas); } void dfs(int node, int idLista) { if (vis[node]) return; vis[node] = true; listas[idLista].push_back(nodes[node]); for (int i = 0; i < ((int)graph[node].size()); i++) { int neighbor = graph[node][i]; if (not vis[neighbor]) dfs(neighbor, idLista); } } int main() { int n, qtdEsq, qtdDir, qtdListas = 0; scanf("%d", &n); memset(idsListas, -1, sizeof idsListas); for (int i = 1; i <= n; i++) { scanf("%d %d", &nodes[i].left, &nodes[i].right); nodes[i].idx = i; if (nodes[i].left != 0) graph[i].push_back(nodes[i].left); if (nodes[i].right != 0) graph[i].push_back(nodes[i].right); } memset(vis, false, sizeof vis); for (int i = 1; i <= n; i++) { if (vis[i]) continue; dfs(i, qtdListas); qtdListas++; } solve(0, 1, qtdListas); for (int i = 1; i <= n; i++) printf("%d %d\n", nodes[i].left, nodes[i].right); return 0; }
#include <bits/stdc++.h> using namespace std; struct node { int l, r; node(int l = 0, int r = 0) : l(l), r(r) {} }; vector<node> v; vector<int> used; void flood(int cur) { if (cur == -1) return; if (used[cur]) return; used[cur] = true; flood(v[cur].l); flood(v[cur].r); } int main() { int n; scanf("%d", &n); v.resize(n); used.resize(n); for (int i = 0; i < n; i++) { int l, r; scanf("%d%d", &l, &r); l--; r--; v[i] = node(l, r); } bool changed = true; while (changed) { changed = false; fill(used.begin(), used.end(), 0); for (int i = 0; i < n && !changed; i++) { if (v[i].r == -1) { flood(i); for (int j = 0; j < n && !changed; j++) { if (!used[j] && v[j].l == -1) { v[i].r = j; v[j].l = i; changed = true; } } } } } for (int i = 0; i < n; i++) printf("%d %d\n", v[i].l + 1, v[i].r + 1); return 0; }
#include <bits/stdc++.h> using namespace std; bool less_vectors(const vector<int>& a, const vector<int>& b) { return a.size() > b.size(); } long long gcd(long long a, long long b) { if (a % b == 0) return b; else return gcd(b, a % b); } class compr { public: bool operator()(pair<pair<int, long long>, int> p1, pair<pair<int, long long>, int> p2) { if (p1.first.second != p2.first.second) return p1.first.second > p2.first.second; else if (p1.second != p2.second) return p1.second > p2.second; else return p1.first < p2.first; } }; long long fastexpo(long long a, long long b) { long long res = 1; while (b > 0) { if (b % 2 == 1) res = (((res) % 1000000007) * ((a) % 1000000007)) % 1000000007; a = (((a) % 1000000007) * ((a) % 1000000007)) % 1000000007; b /= 2; } return res; } long long fastexpom(long long a, long long b, long long m) { long long res = 1; while (b > 0) { if (b % 2 == 1) res = (((res) % m) * ((a) % m)) % m; a = (((a) % m) * ((a) % m)) % m; b /= 2; } return res; } long long modinv(long long a, long long m = 1000000007) { return fastexpom(a, m - 2, m); } vector<vector<int> > g(101); vector<vector<int> > ng(101); int pl; vector<int> vis(101); void dfs(int s, int p) { vector<int>::iterator it = g[s].begin(); ng[p].push_back(s); int j = 0; for (; it != g[s].end(); it++) { j++; if (*it != 0 && *it != p && !vis[*it]) { vis[*it] = 1; dfs(*it, s); ng[s].push_back(*it); } else if (*it == 0) { pl = s; } } return; } vector<pair<int, int> > ans; int main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); ; int n; cin >> n; int l; int r; for (int i = 0; i < n; i++) { cin >> l >> r; g[l].push_back(i + 1); g[i + 1].push_back(r); } for (int i = 0; i < g[0].size(); i++) { if (i == 0) pl = g[0][i]; else ng[pl].push_back(g[0][i]); vis[g[0][i]] = 1; dfs(g[0][i], i ? pl : 0); if (i == g[0].size() - 1) ng[pl].push_back(0); } ans.resize(n + 1); for (int i = 1; i <= n; i++) { ans[i].second = ng[i][0]; ans[ng[i][0]].first = i; } for (int i = 1; i <= n; i++) cout << ans[i].first << " " << ans[i].second << "\n"; return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n, l[101] = {}, r[101] = {}, cl = 0, sl[101] = {}; cin >> n; for (int i = 1; i <= n; ++i) { cin >> l[i] >> r[i]; if (l[i] == 0) sl[cl++] = i; } for (int i = 0; i < cl - 1; ++i) { int j = sl[i]; while (r[j] != 0) { j = r[j]; } r[j] = sl[i + 1]; l[sl[i + 1]] = j; } cout << endl; for (int i = 1; i <= n; ++i) { cout << l[i] << " " << r[i] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const int N = 110; struct Node { int a; int b; int c; }; Node node[N]; int n; queue<int> Q; int dfs(int x) { if (node[x].c == 0) { return x; } return dfs(node[x].c); } int main() { int mark; int ne; while (scanf("%d", &n) == 1) { mark = 1; while (!Q.empty()) { Q.pop(); } for (int i = 1; i <= n; i++) { scanf("%d%d", &node[i].a, &node[i].c); node[i].b = i; if (!node[i].a) { Q.push(i); } } while (!Q.empty()) { int now; now = Q.front(); Q.pop(); if (!mark) { node[now].a = ne; node[ne].c = now; } mark = 0; ne = dfs(now); } for (int i = 1; i <= n; i++) { printf("%d %d\n", node[i].a, node[i].c); } } return 0; }
#include <bits/stdc++.h> using namespace std; const long long mod = 1e9 + 7; const long long sz = 100005; int a[105][2], n, zero1, zero2; int main() { cin >> n; for (int i = 1; i <= n; i++) { cin >> a[i][0] >> a[i][1]; if (a[i][0] == 0) zero1++; if (a[i][1] == 0) zero2++; } int end; bool stop = 0; for (int i = 1; i <= n; i++) { if (a[i][0] == 0) { end = i; while (!stop) { stop = 1; while (a[end][1] != 0) end = a[end][1]; for (int j = 1; j <= n; j++) { if (i == j) continue; if (a[j][0] == 0) { a[j][0] = end; a[end][1] = j; end = j; stop = 0; break; } } } } } for (int i = 1; i <= n; i++) { cout << a[i][0] << " " << a[i][1] << '\n'; } }
#include <bits/stdc++.h> int dx[] = {-1, -1, -1, 0, 1, 1, 1, 0}; int dy[] = {-1, 0, 1, 1, 1, 0, -1, -1}; using namespace std; long long power(long long a, long long p, long long M) { long long r = 1; a = a % M; while (p > 0) { if (p % 2) r = (r * a) % M; a = (a * a) % M; p /= 2; } return r; } long long gcd(long long a, long long b) { if (b == 0) return a; return gcd(b, a % b); } int n; deque<int> dq[105]; int l[105], r[105]; bool check[105]; int leftt[105], rightt[105]; void solve() { cin >> n; if (0) cout << "n" << " : " << n << endl; ; for (int i = 1; i < n + 1; i++) { int a, b; cin >> a >> b; l[i] = a, r[i] = b; } int c = 0; deque<int> q; if (0) cout << "1" << " : " << 1 << endl; ; do { q.clear(); for (int i = 1; i < n + 1; i++) { if (!check[i]) { if (0) cout << "i" << " : " << i << endl; ; q.push_front(i); check[i] = 1; int x = i; while (1) { if (l[x]) q.push_front(l[x]), x = l[x]; else { for (int j = 1; j < n + 1; j++) { if (r[j] == x) q.push_front(j), x = j; } } if (check[x]) break; check[x] = 1; } x = i; while (r[x]) { if (r[x]) q.push_back(r[x]), x = r[x]; else { for (int j = 1; j < n + 1; j++) { if (l[j] == x) q.push_back(j), x = j; } } if (check[x]) break; check[x] = 1; } break; } } if (q.size()) dq[c++] = q; } while (q.size()); if (0) cout << "c" << " : " << c << endl; ; vector<int> ans; for (int i = 0; i < c; i++) { if (0) cout << "i" << " : " << i << endl; ; for (auto x : dq[i]) ans.push_back(x); } for (int i = 0; i < ans.size(); i++) { if (i == 0) leftt[ans[i]] = 0; else leftt[ans[i]] = ans[i - 1]; if (i == ans.size() - 1) rightt[ans[i]] = 0; else rightt[ans[i]] = ans[i + 1]; } for (int i = 1; i < n + 1; i++) cout << leftt[i] << ' ' << rightt[i] << endl; } int main() { solve(); return 0; }
#include <bits/stdc++.h> using namespace std; int parent[107], sz[107], ans[107], cont, n; pair<int, int> print[107]; bool compare(int a, int b) { return sz[a] > sz[b]; } int find(int a) { if (parent[a] == a) return a; return parent[a] = find(parent[a]); } void unhonho(int a, int b) { int A = find(a); int B = find(b); if (A == B) return; if (sz[A] < sz[B]) { parent[A] = B; sz[B] += sz[A]; } else { parent[B] = A; sz[A] += sz[B]; } } map<int, int> liga; void dfs(int no) { if (no == n + 1) return; ans[cont++] = no; dfs(liga[no]); } vector<int> ini; int main() { cin >> n; for (int i = 1; i <= n; i++) { int l, r; cin >> l >> r; if (r == 0) r = n + 1; liga[l] = i; liga[i] = r; if (l != 0) unhonho(l, i); else ini.push_back(i); if (r != n + 1) unhonho(i, r); } sort(ini.begin(), ini.end(), compare); cont = 1; for (int i = 0; i < ini.size(); i++) { dfs(ini[i]); } for (int i = 1; i <= n; i++) { print[ans[i]] = make_pair(ans[i - 1], ans[i + 1]); } for (int i = 1; i <= n; i++) { cout << print[i].first << " " << print[i].second << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; using pii = pair<int, int>; using vi = vector<int>; using ll = long long; int main() { ios_base::sync_with_stdio(0); cin.tie(0); int n; cin >> n; vi l(n), r(n); for (int i = int(0); i < int(n); i++) { cin >> l[i] >> r[i]; l[i]--, r[i]--; } stack<pii> lists; for (int i = int(0); i < int(n); i++) { if (l[i] == -1) { int start = i, end = i; while (r[end] != -1) end = r[end]; lists.emplace(start, end); } } while (int((lists).size()) >= 2) { auto [start1, end1] = lists.top(); lists.pop(); auto [start2, end2] = lists.top(); lists.pop(); r[end1] = start2; l[start2] = end1; lists.emplace(start1, end2); } for (int i = int(0); i < int(n); i++) cout << l[i] + 1 << ' ' << r[i] + 1 << '\n'; return 0; }
#include <bits/stdc++.h> const long long INF = 1e18 + 1; const long long N = 1e5; const long long MOD = 1e18 + 1; using namespace std; pair<long long, long long> b[1000]; vector<vector<long long> > g(N + 5); long long n, m, k, r, x, y, l, c, t, cur, last, ans, mn(INF), mx(-INF), a[N + 5]; bool f; int main() { cin >> n; f = false; for (int i = 1; i <= n; i++) { cin >> b[i].first >> b[i].second; } for (int i = 1; i <= n; i++) { if (b[i].first == 0) { if (!f) { f = true; long long j = i; last = i; while (b[j].second != 0) { j = b[j].second; last = j; } } else { b[i].first = last; b[last].second = i; long long j = i; last = i; while (b[j].second != 0) { j = b[j].second; last = j; } } } } for (int i = 1; i <= n; i++) { cout << b[i].first << " " << b[i].second << "\n"; } return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n = 0, a[110] = {0}, b[110], c[110], k = 1; cin >> n; for (int i = 1; i <= n; i++) cin >> b[i] >> c[i]; for (int i = 1; i <= n; i++) { if (b[i] == 0) { a[k++] = i; int z = i; while (c[z] != 0) for (int j = 1; j <= n; j++) if (b[j] == z) { a[k++] = j; z = j; break; } } } for (int i = 1; i <= n; i++) { for (int j = 1; i <= n; j++) if (a[j] == i && j == 1) { cout << '0' << ' ' << a[j + 1]; break; } else if (a[j] == i && j == n) { cout << a[j - 1] << ' ' << '0'; break; } else if (a[j] == i) { cout << a[j - 1] << ' ' << a[j + 1]; break; } cout << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const long long MOD = 998244353; const long long MAX = 1000000000; const long long LLONG = 9223372036854775807; const int N = 100000; const double EPS = 0.00000001; const int sqsz = 5000; template <typename T> inline int sgn(const T& val) { return (T(0) < val) - (val < T(0)); } inline unsigned long long hsh(int x, int y) { return (((unsigned long long)x) << 32) + y; } template <typename T> inline T gcd(T a, T b) { while (b) { a %= b; swap(a, b); } return a; } inline void fastio() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); } int main() { int l[100], r[100]; vector<int> lists[100]; int n, cn = 0; bool fl = true; scanf("%i", &n); for (int i = 0; i < n; i++) { scanf("%i %i", l + i, r + i); } for (int i = 0; i < n; i++) if (!l[i]) { lists[cn].push_back(i); int j = i; while (r[j]) { j = r[j] - 1; lists[cn].push_back(j); } cn++; } for (int i = 1; i < cn; i++) { r[*(lists[i - 1].end() - 1)] = (*lists[i].begin()) + 1; l[*lists[i].begin()] = (*(lists[i - 1].end() - 1)) + 1; } for (int i = 0; i < n; i++) { printf("%i %i\n", l[i], r[i]); } }
#include <bits/stdc++.h> using namespace std; void out() { cout << -1; exit(0); } const double eps = 1e-7; const int N = 2e6 + 9; int l[110], r[110], n, ans, s, f; int main() { cin >> n; for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; } for (int i = 1; i <= n; i++) if (!l[i]) { r[f] = i; l[i] = f; f = i; while (r[f]) f = r[f]; } for (int i = 1; i <= n; i++) { cout << l[i] << " " << r[i] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const int l = 0; const int r = 1; int main() { int n; cin >> n; int A[n + 1][2]; int B[n + 1][2]; bool was[n + 1]; for (int i = 0; i <= n; i++) { was[i] = false; B[i][l] = 0; B[i][r] = 0; } for (int i = 1; i <= n; i++) { cin >> A[i][l] >> A[i][r]; } int last = 0; for (int i = 1; i <= n; i++) { if (A[i][l] == 0) { last = i; break; } } for (int z = 0; z < n; z++) { B[last][l] = A[last][l]; B[last][r] = A[last][r]; was[last] = true; if (B[last][r] == 0) { for (int i = 1; i <= n; i++) { if (A[i][l] == 0 && !was[i]) { A[i][l] = last; B[last][r] = i; last = i; break; } } } else last = B[last][r]; } for (int i = 1; i <= n; i++) cout << B[i][l] << ' ' << B[i][r] << endl; return 0; }
#include <bits/stdc++.h> int main() { int n, l[105][2] = {}, i, j; scanf("%d", &n); for (i = 1; i <= n; i++) scanf("%d %d", &l[i][0], &l[i][1]); int head[105], tail[105], pt = 0, cur; for (i = 1; i <= n; i++) if (l[i][0] == 0) { head[pt] = i; cur = i; while (l[cur][1] != 0) cur = l[cur][1]; tail[pt] = cur; pt++; } for (i = 1; i < pt; i++) { l[tail[i]][1] = head[i - 1]; l[head[i - 1]][0] = tail[i]; } for (i = 1; i <= n; i++) printf("%d %d\n", l[i][0], l[i][1]); return 0; }
#include <bits/stdc++.h> using namespace std; int l[110], r[110], u[110], v[110], c, tmp, vis[110]; int main() { cin.tie(0); ios_base::sync_with_stdio(false); int n; cin >> n; for (int i = 1; i <= n; i++) cin >> l[i] >> r[i]; for (int i = 1; i <= n; i++) { if (l[i]) r[l[i]] = i; if (r[i]) l[r[i]] = i; } for (int i = 1; i <= n; i++) { int x = i; if (!l[i]) { if (tmp) { r[tmp] = i; l[i] = tmp; } while (r[x]) { x = r[x]; } tmp = x; } } for (int i = 1; i <= n; i++) cout << l[i] << " " << r[i] << endl; return 0; }
#include <bits/stdc++.h> using namespace std; struct TnT { int l, r; } T[111]; bool check(int i, int j) { int t1 = T[i].l, t2 = T[j].r; while (1) { if (t1 == 0 || t2 == 0) return 1; if ((t1 == j && t2 == i) || t1 == t2) return 0; t1 = T[t1].l; t2 = T[t2].r; } } int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { cin >> T[i].l >> T[i].r; } if (n == 1) { cout << T[1].l << " " << T[1].r << endl; return 0; } for (int i = 1; i <= n; i++) { if (T[i].r == 0) { for (int j = 1; j <= n; j++) { if (i == j) continue; if (T[j].l == 0 && check(i, j)) { T[i].r = j; T[j].l = i; break; } } } } for (int i = 1; i <= n; i++) { cout << T[i].l << " " << T[i].r << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const int maxn = 110; int l[maxn]; int r[maxn]; int a[maxn]; int la; int ansl[maxn]; int ansr[maxn]; int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d %d", l + i, r + i); for (int i = 1; i <= n; i++) if (l[i] == 0) for (int j = i; j != 0; j = r[j]) a[++la] = j; if (n == 1) { printf("0 0\n"); return 0; } for (int i = 1; i <= n; i++) { ansl[a[i]] = a[i - 1]; ansr[a[i]] = a[i + 1]; } for (int i = 1; i <= n; i++) printf("%d %d\n", ansl[i], ansr[i]); return 0; }
#include <bits/stdc++.h> const int maxn = 1e2 + 10; using namespace std; struct node { int l, r; node() { l = 0; r = 0; } } a[maxn]; int idx[maxn]; int Find(int n) { if (a[n].r) { return Find(a[n].r); } else return n; } int main() { int n; while (~scanf("%d", &n)) { int l, r; int cnt = 0; for (int i = 1; i <= n; i++) { scanf("%d%d", &l, &r); a[i].l = l; a[i].r = r; if (l == 0) { idx[cnt++] = i; } } for (int i = 0; i < cnt - 1; i++) { int st = idx[i]; int it = Find(st); a[it].r = idx[i + 1]; a[idx[i + 1]].l = it; } for (int i = 1; i <= n; i++) { printf("%d %d\n", a[i].l, a[i].r); } } return 0; }
#include <bits/stdc++.h> using namespace std; long long MOD = 1e9 + 7; bool debug = 1; pair<int, int> vp[110]; int bunda(int ii) { if (vp[ii].second == 0) return ii; return bunda(vp[ii].second); } int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; i++) { scanf("%d%d", &vp[i].first, &vp[i].second); } bool jal = 0; int l0 = -1, r0; for (int i = 1; i <= n; i++) { if (vp[i].first == 0) { if (jal) { vp[i].first = r0; vp[r0].second = i; r0 = bunda(r0); } else { jal = 1; l0 = i; r0 = bunda(l0); } } } for (int i = 1; i <= n; i++) { printf("%d %d\n", vp[i].first, vp[i].second); } return 0; }
#include <bits/stdc++.h> using namespace std; int l[105], r[105]; bool visted[105]; int find_left(int x) { visted[x] = true; if (l[x] == 0) return x; else return find_left(l[x]); } int find_right(int x) { visted[x] = true; if (r[x] == 0) return x; else return find_right(r[x]); } int main() { int n; scanf("%d", &n); memset(visted, false, sizeof(visted)); for (int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]); int left_ = find_left(1); int right_ = find_right(1); int left_1, right_1; for (int i = 2; i <= n; i++) { if (!visted[i]) { left_1 = find_left(i); right_1 = find_right(i); l[left_1] = right_; r[right_] = left_1; right_ = right_1; } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; vector<vector<int> > g; vector<int> order; vector<bool> used; void top_sort(int v) { used[v] = 1; for (int cur : g[v]) if (!used[cur]) top_sort(cur); order.push_back(v); } int main() { int n; cin >> n; g.resize(n); used.resize(n, 0); vector<int> c(n, -1), p(n, -1); for (int i = 0, l, r; i < n; i++) { cin >> l >> r; l--, r--; if (r != -1) g[i].push_back(r), c[i] = r, p[r] = i; } for (int i = 0; i < n; i++) if (!used[i] && p[i] == -1) top_sort(i); reverse(order.begin(), order.end()); for (int i = 0; i < order.size(); i++) { int cur = order[i]; if (c[cur] != -1) continue; for (int j = i + 1; j < order.size(); j++) { int t = order[j]; if (p[t] == -1) { p[t] = cur; c[cur] = t; break; } } } for (int i = 0; i < n; i++) cout << p[i] + 1 << " " << c[i] + 1 << endl; }
#include <bits/stdc++.h> const int N = 1002; struct Two { int li, ri; } S[N]; int n, l[N], r[N], s, u, v; bool vis[N]; int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d%d", l + i, r + i); for (int i = 1; i <= n; i++) if (!vis[i]) { vis[u = i] = 1; while (l[u]) vis[u = l[u]] = 1; vis[v = i] = 1; while (r[v]) vis[v = r[v]] = 1; S[++s] = (Two){u, v}; } for (int i = 1; i <= s - 1; i++) { r[S[i].ri] = S[i + 1].li; l[S[i + 1].li] = S[i].ri; } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int N = 1e2 + 10; int in[N], out[N], I, O; struct DoublyLink { int l, r; } z[N]; int n; int ds[N]; int dsu(int x) { return ds[x] == x ? x : dsu(ds[x]); } int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) ds[i] = i; for (int i = 1; i <= n; i++) { scanf("%d%d", &z[i].l, &z[i].r); if (z[i].l != 0) { ds[dsu(z[i].l)] = dsu(i); } if (z[i].r != 0) { ds[dsu(z[i].r)] = dsu(i); } } for (int i = 1; i <= n; i++) { for (int j = i + 1; j <= n; j++) { if (dsu(i) == dsu(j)) continue; if (z[i].l == 0) { if (z[j].r == 0) { z[i].l = j; z[j].r = i; ds[dsu(i)] = dsu(j); } } if (dsu(i) == dsu(j)) continue; if (z[i].r == 0) { if (z[j].l == 0) { z[i].r = j; z[j].l = i; ds[dsu(i)] = dsu(j); } } } } for (int i = 1; i <= n; i++) printf("%d %d\n", z[i].l, z[i].r); }
#include <bits/stdc++.h> #pragma comment(linker, "/STACK:36777216") using namespace std; int main() { int n; cin >> n; vector<int> prev(n, -1), nxt(n, -1); for (int i = 0; i < n; i++) { int a, b; cin >> a >> b; prev[i] = a - 1; nxt[i] = b - 1; } vector<pair<int, int>> lists; for (int i = 0; i < n; i++) { if (prev[i] == -1) { int cur = i; while (nxt[cur] != -1) cur = nxt[cur]; lists.emplace_back(i, cur); } } for (int i = 0; i < lists.size() - 1; i++) { prev[lists[i + 1].first] = lists[i].second; nxt[lists[i].second] = lists[i + 1].first; } for (int i = 0; i < n; i++) cout << prev[i] + 1 << ' ' << nxt[i] + 1 << '\n'; return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; int dados[n][3]; int inicios[n]; int finais[n]; int listas = 0; for (int i = 0; i < n; i++) { cin >> dados[i][0]; cin >> dados[i][2]; dados[i][1] = i + 1; if (dados[i][0] == 0) { inicios[listas] = i; listas++; } } int atual, atualProximo; for (int i = 0; i < listas; i++) { atual = inicios[i]; while (dados[atual][2] != 0) { atualProximo = dados[atual][2] - 1; atual = atualProximo; } finais[i] = atual; } for (int i = 0; i < listas - 1; i++) { dados[finais[i]][2] = inicios[i + 1] + 1; dados[inicios[i + 1]][0] = finais[i] + 1; } for (int i = 0; i < n; i++) { cout << dados[i][0] << " " << dados[i][2] << endl; } }
#include <bits/stdc++.h> using namespace std; struct node { int i; int left; int right; }; int main() { int n; scanf("%d", &n); vector<node*> nodes; vector<node*> starts; for (int i = 0; i < n; i++) { node* new_node = new node(); int a, b; scanf("%d %d", &a, &b); new_node->left = a - 1; new_node->right = b - 1; new_node->i = i; if (a == 0) { starts.push_back(new_node); } nodes.push_back(new_node); } node* end = starts[0]; while (end->right != -1) { end = nodes[end->right]; } for (int i = 1; i < starts.size(); i++) { end->right = starts[i]->i; starts[i]->left = end->i; end = starts[i]; while (end->right != -1) { end = nodes[end->right]; } } for (int i = 0; i < n; i++) { printf("%d %d\n", nodes[i]->left + 1, nodes[i]->right + 1); } }
#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; unordered_map<int, pair<int, int>> list; vector<int> starts; for (int i = 0; i < n; i++) { int a, b; cin >> a >> b; if (a == 0) { starts.push_back(i + 1); } list[i + 1] = make_pair(a, b); } sort(starts.begin(), starts.end()); for (int i = 0; i < starts.size() - 1; i++) { int current = starts[i]; while (list[current].second != 0) { current = list[current].second; } list[current].second = starts[i + 1]; list[starts[i + 1]].first = current; } for (int i = 1; i < n + 1; i++) { cout << list[i].first << " " << list[i].second << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; vector<int> padre, si; int getPadre(int x) { int pa = padre[x]; if (padre[x] != x) { pa = getPadre(padre[x]); } padre[x] = pa; return pa; } void merge(int x, int y) { int px = getPadre(x); int py = getPadre(y); if (si[px] < si[py]) { padre[px] = py; } else { padre[py] = px; if (si[px] == si[py]) si[py]++; } } bool conn(int x, int y) { return getPadre(x) == getPadre(y); } int main() { int n; cin >> n; vector<int> voy(n + 1), viene(n + 1); for (int i = 0; i < (int)(n + 1); i++) { padre.push_back(i); si.push_back(1); } vector<int> sinviene, sinvoy; for (int i = 0; i < (int)(n); i++) { int l, r; cin >> l >> r; voy[i + 1] = r; viene[i + 1] = l; if (!r) sinvoy.push_back(i + 1); else merge(i + 1, r); if (!l) sinviene.push_back(i + 1); else merge(i + 1, l); } int iviene = 0; while (iviene < (int)sinviene.size()) { int svoy = sinvoy[iviene]; for (int i = 0; i < (int)(n + 1); i++) { if (i == 0) continue; if (viene[i] != 0) continue; if (!conn(i, svoy)) { viene[i] = svoy; voy[svoy] = i; merge(svoy, i); break; } } iviene++; } for (int i = 0; i < (int)(n); i++) { cout << viene[i + 1] << " " << voy[i + 1] << endl; } }
#include <bits/stdc++.h> using namespace std; const int maxn = 107; int pre[maxn], nex[maxn]; vector<int> rcd[maxn]; void Deal(int st, int k) { int pos = st; rcd[k].push_back(pos); while (nex[pos] != 0) { pos = nex[pos]; rcd[k].push_back(pos); } } int main() { int n, num = 0; cin >> n; for (int i = 1; i <= n; i++) cin >> pre[i] >> nex[i]; for (int i = 1; i <= n; i++) { if (!pre[i]) Deal(i, ++num); } for (int i = 1; i < num; i++) { int t = rcd[i].size(); int s1 = rcd[i][t - 1], s2 = rcd[i + 1][0]; nex[s1] = s2; pre[s2] = s1; } for (int i = 1; i <= n; i++) cout << pre[i] << " " << nex[i] << endl; return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n, i; cin >> n; int l[200], r[200]; vector<vector<int> > lists; for (i = 1; i <= n; i++) { cin >> l[i] >> r[i]; if (l[i] == 0) { vector<int> temp; temp.push_back(i); lists.push_back(temp); } } int numLL = lists.size(); for (i = 0; i < numLL; i++) { int j = lists[i][0]; while (r[j] != 0) { lists[i].push_back(r[j]); j = r[j]; } } vector<int> result; for (i = 0; i < numLL; i++) result.insert(result.end(), lists[i].begin(), lists[i].end()); for (i = 1; i <= n; i++) { auto it = find(result.begin(), result.end(), i); int idx = it - result.begin(); if (idx > 0) cout << result[idx - 1]; else cout << 0; cout << " "; if (idx < n - 1) cout << result[idx + 1]; else cout << 0; cout << endl; } }
#include <bits/stdc++.h> using namespace std; const int MAX_N = 100 + 10; int p[MAX_N], n[MAX_N]; list<int> head; int pop() { int v = head.front(); head.pop_front(); return v; } int main() { int N; cin >> N; for (int i = 1; i <= N; ++i) { cin >> p[i] >> n[i]; if (!p[i]) { head.push_back(i); } } int c = pop(); while (!head.empty()) { while (n[c]) { c = n[c]; } n[c] = pop(); p[n[c]] = c; } for (int i = 1; i <= N; ++i) { cout << p[i] << " " << n[i] << endl; } return 0; }
#include <bits/stdc++.h> int zuo[105]; int you[105]; int z[105]; int y[105]; int main() { int a; while (~scanf("%d", &a)) { int zr = 1, yr = 1; for (int i = 1; i <= a; i++) { scanf("%d%d", &zuo[i], &you[i]); if (you[i] == 0) { z[zr] = i; zr++; } } memset(y, 0, sizeof(y)); int zc = 1; int yc = 0; for (int i = 1; i <= a; i++) { if (zuo[i] == 0 && zc < zr - 1) { int k = you[i]; while (you[k] != 0) { k = you[k]; } if (z[zc] == k || z[zc] == i) { int zhong = z[zc]; zc++; while (y[z[zc]] == 1) zc++; zuo[i] = z[zc]; you[z[zc]] = i; z[zc] = zhong; } else { zuo[i] = z[zc]; you[z[zc]] = i; zc++; } while (y[z[zc]] == 1) zc++; } } for (int i = 1; i <= a; i++) { printf("%d %d\n", zuo[i], you[i]); } } return 0; }
#include <bits/stdc++.h> using namespace std; const int mx = 100100; const int md = 1e9 + 7; const double EULER = 2.71828182845904523536; double pitagoras(double x1, double y1, double x2, double y2) { return sqrt(pow(abs(x1 - x2), 2) + pow(abs(y1 - y2), 2)); } int main() { int n, arr[110][3], visit[110] = {}, a, p = 1, depan = 0, belakang = 0; scanf("%d", &n); for (int i = 0; i < n; i += 1) { scanf("%d %d", &arr[i][0], &arr[i][1]); if (arr[i][0] == 0) depan++; } for (int i = 0; i < n; i += 1) { if (visit[i] == 0) { visit[i] = i + 1; a = i; while (arr[a][0] != 0 and visit[arr[a][0] - 1] == 0) { a = arr[a][0] - 1; visit[a] = i + 1; } a = i; while (arr[a][1] != 0 and visit[arr[a][1] - 1] == 0) { a = arr[a][1] - 1; visit[a] = i + 1; } } } a = 1; while (depan > 1) { visit[a - 1] = 1; if (arr[a - 1][1] == 0) { for (int i = 0; i < n; i += 1) { if (visit[a - 1] != visit[i] and arr[i][0] == 0) { arr[i][0] = a; arr[a - 1][1] = i + 1; depan--; break; } } } a = arr[a - 1][1]; } for (int i = 0; i < n; i += 1) cout << arr[i][0] << " " << arr[i][1] << endl; }
#include <bits/stdc++.h> using namespace std; int n, l[100010], r[100010]; int main() { if (fopen("a.txt", "r")) { freopen("a.txt", "r", stdin); } else ios_base::sync_with_stdio(false); cin.tie(NULL); cin >> n; for (int i = 1; i <= n; i++) cin >> l[i] >> r[i]; vector<int> v; for (int i = 1; i <= n; i++) if (l[i] == 0) { v.push_back(i); } int now = v.back(), d = 0; while (true) { now = v.back(); v.pop_back(); d++; while (r[now] != 0) { now = r[now]; d++; } if (d == n) break; int nex = v.back(); l[nex] = now; r[now] = nex; } for (int i = 1; i <= n; i++) cout << l[i] << ' ' << r[i] << '\n'; }
#include <bits/stdc++.h> using namespace std; inline int read() { int x = 0, f = 1; char ch = getchar(); while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); } while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); } return x * f; } int n, l[100 + 5], r[100 + 5], From = 0, To = 0; queue<int> q1; int main() { n = read(); for (int i = 1; i <= n; ++i) { l[i] = read(); r[i] = read(); if (!l[i]) if (!From) From = i; else q1.push(i); } for (int i = From;;) { if (!r[i]) { if (!q1.size()) break; r[i] = q1.front(), q1.pop(), l[r[i]] = i; } i = r[i]; } for (int i = 1; i <= n; ++i) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int maxn = 1e6 + 50; const int inf = 0x3f3f3f3f; struct node { int l, r; int i; } a[150]; int main() { int n; cin >> n; vector<deque<int> > b; for (int i = 1; i <= n; ++i) { cin >> a[i].l >> a[i].r; a[i].i = i; } for (int i = 1; i <= n; ++i) { if (a[i].l == 0 && a[i].r != 0) { deque<int> b1; b1.push_back(i); b1.push_back(a[i].r); while (a[b1.back()].r != 0) { b1.push_back(a[b1.back()].r); } b.push_back(b1); } if (a[i].l == 0 && a[i].r == 0) { deque<int> b1; b1.push_back(i); b.push_back(b1); } } if (b.size() == 1) { for (int i = 1; i <= n; ++i) cout << a[i].l << " " << a[i].r << endl; } else { for (int i = b.size() - 1; i > 0; --i) { a[b[i].front()].l = b[i - 1].back(); a[b[i - 1].back()].r = b[i].front(); } for (int i = 1; i <= n; ++i) cout << a[i].l << " " << a[i].r << endl; } }
#include <bits/stdc++.h> using namespace std; const int N = 105; int n; int l[N], r[N]; int head[N], tail[N]; int nh, nt; int fa[N]; int find(int x) { return x == fa[x] ? x : (fa[x] = find(fa[x])); } struct Node { int head, tail; Node() {} Node(int h, int t) : head(h), tail(t) {} } p[N]; int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) fa[i] = i; for (int i = 1; i <= n; i++) { scanf("%d%d", l + i, r + i); if (l[i]) fa[i] = l[i]; else head[++nh] = i; if (r[i]) fa[r[i]] = i; else tail[++nt] = i; } for (int i = 1; i <= nh; i++) { p[i] = Node(find(tail[i]), tail[i]); } for (int i = 2; i <= nt; i++) { r[p[1].tail] = p[i].head; l[p[i].head] = p[1].tail; p[1].tail = p[i].tail; } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; int l[105]; int r[105]; int id[105]; void dfs(int cur, int i) { id[cur] = i; if (r[cur]) dfs(r[cur], i); } int main() { int n, cnt = 0, c2; scanf("%d", &n); for (int i = 1; i <= n; i++) { scanf("%d%d", &l[i], &r[i]); if (!l[i]) cnt++; } c2 = cnt; for (int i = 1; i <= n; i++) { if (!l[i]) dfs(i, c2--); } for (int i = 1; i < cnt; i++) { for (int en = 1; en <= n; en++) { if (r[en] || id[en] != i) continue; for (int st = 1; st <= n; st++) { if (l[st] || id[st] != i + 1) continue; l[st] = en, r[en] = st; } } } for (int i = 1; i <= n; i++) { printf("%d %d\n", l[i], r[i]); } }
#include <bits/stdc++.h> using namespace std; const long double PI = acos(-1); const int INF = (int)1e9; const long long INFF = (long long)1e18; const int mod = (int)1e9 + 7; const int MXN = (int)2e5 + 7; int ll[MXN], rr[MXN]; int gp[MXN], lv[MXN], rv[MXN]; int fd(int v) { return gp[v] == v ? v : gp[v] = fd(gp[v]); } int num; void uni(int u, int v) { u = fd(u); v = fd(v); if (u == v) return; num--; rv[rr[u]] = ll[v]; lv[ll[v]] = rr[u]; gp[u] = v; ll[v] = ll[u]; } int main(void) { int n; scanf("%d", &n); num = n; for (int i = 1; i < n + 1; ++i) gp[i] = i, ll[i] = i, rr[i] = i; for (int i = 1; i < n + 1; ++i) { int l, r; scanf("%d %d", &l, &r); if (l) uni(l, i); if (r) uni(i, r); } while (num > 1) { int u = fd(1); for (int i = 1; i < n + 1; ++i) if (fd(i) != u) { uni(u, i); } } for (int i = 1; i < n + 1; ++i) printf("%d %d\n", lv[i], rv[i]); return 0; }
#include <bits/stdc++.h> using namespace std; int n; int counter = 0; int l[101], r[101], lm[101], rm[101]; void dfs(int s) { if (l[s] != 0) lm[s] = lm[l[s]]; if (r[s] != 0) dfs(r[s]); } void dfs2(int s) { if (r[s] != 0) rm[s] = rm[r[s]]; if (l[s] != 0) dfs2(l[s]); } int main() { cin >> n; for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; } for (int i = 1; i <= n; i++) { counter++; lm[i] = i; rm[i] = i; dfs(i); dfs2(i); } set<pair<int, int> > s; for (int i = 1; i <= n; i++) { s.insert(make_pair(lm[i], rm[i])); } vector<pair<int, int> > v(begin(s), end(s)); for (int i = 1; i < v.size(); i++) { l[v[i].first] = v[i - 1].second; r[v[i - 1].second] = v[i].first; } for (int i = 1; i <= n; i++) { cout << l[i] << " " << r[i] << "\n"; } }
#include <bits/stdc++.h> using namespace std; class DisjointSet { public: vector<int> parent; DisjointSet(int n) : parent(n) { for (int i = 0; i < n; i++) parent[i] = i; } void join(int a, int b) { parent[find(b)] = find(a); } int find(int a) { return a == parent[a] ? a : parent[a] = find(parent[a]); } bool check(int a, int b) { return find(a) == find(b); } }; int main() { int n; cin >> n; vector<int> l(n + 1), r(n + 1); DisjointSet ds(n + 1); for (int i = 1; i <= n; i++) { cin >> l[i] >> r[i]; if (l[i]) ds.join(i, l[i]); if (r[i]) ds.join(i, r[i]); if (l[i] && r[i]) ds.join(l[i], r[i]); } for (int i = 1; i <= n; i++) { if (l[i] && r[i]) continue; for (int j = i + 1; j <= n; j++) { if (l[j] && r[j]) continue; if ((!l[i] && !r[j]) || (!r[i] && !l[j])) { if (ds.check(i, j)) continue; ds.join(i, j); if (!l[i] && !r[j]) { l[i] = j; r[j] = i; } else if (!r[i] && !l[j]) { r[i] = j; l[j] = i; } } } } for (int i = 1; i <= n; i++) cout << l[i] << " " << r[i] << '\n'; }
#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; int adj[n + 1][2]; int a, b; for (int i = 1; i < n + 1; i++) { cin >> a >> b; adj[i][0] = a; adj[a][1] = i; adj[i][1] = b; adj[b][0] = i; } int end = 0; for (int i = 1; i < n + 1; i++) { if (adj[i][0] == 0) { adj[end][1] = i; adj[i][0] = end; int cur = i; while (adj[cur][1] != 0) { cur = adj[cur][1]; } end = cur; } } for (int i = 1; i < n + 1; i++) { cout << adj[i][0] << " " << adj[i][1] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n, a[101][2], k; vector<pair<int, int>> A; cin >> n; for (int i = 1; i <= n; i++) for (int u = 0; u < 2; u++) cin >> a[i][u]; for (int i = 1; i <= n; i++) if (!a[i][0]) { k = i; int k1 = k; while (a[k1][1]) k1 = a[k1][1]; A.push_back(pair<int, int>{k, k1}); } for (int i = 0; i < A.size() - 1; i++) { a[A[i].second][1] = A[i + 1].first; a[A[i + 1].first][0] = A[i].second; } for (int i = 1; i <= n; i++) { for (int u = 0; u < 2; u++) cout << a[i][u] << ' '; cout << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; int arr[200][2]; int vis[200]; vector<int> f; int main() { std::ios::sync_with_stdio(false); int n; int i; cin >> n; int nf = 0, nb = 0; for (i = 1; i <= n; i++) { int a, b; cin >> a >> b; if (a == 0) nf++; if (b == 0) nb++; arr[i][0] = a; arr[i][1] = b; } for (i = 1; i <= n; i++) { if (nf == 1 && nb == 1) break; int j; if (arr[i][0] == 0) { int cur = i; while (arr[cur][1]) { cur = arr[cur][1]; } for (j = 1; j <= n; j++) { if (arr[j][0] == 0 && j != i) { arr[cur][1] = j; arr[j][0] = cur; j = n + 1; nf--; nb--; } } } } for (i = 1; i <= n; i++) { cout << arr[i][0] << " " << arr[i][1] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; vector<long long> L, R; int dfs(int v) { if (R[v] == 0) return v; return dfs(R[v]); } int main() { ios::sync_with_stdio(0); cin.tie(0); int n; cin >> n; L = R = vector<long long>(n + 1); for (int i = 1; i <= n; ++i) cin >> L[i] >> R[i]; vector<long long> TL, TR; for (int i = 1; i <= n; ++i) { if (L[i] == 0) { TL.push_back(i); TR.push_back(dfs(i)); } } for (int i = 1; i < TL.size(); ++i) { R[TR[i - 1]] = TL[i]; L[TL[i]] = TR[i - 1]; } for (int i = 1; i <= n; ++i) cout << L[i] << " " << R[i] << "\n"; return 0; }
#include <bits/stdc++.h> using namespace std; int n; int l[111]; int r[111]; int gre(int c) { while (r[c]) c = r[c]; return c; } int main() { cin >> n; for (int i = 1; i <= n; ++i) { cin >> l[i] >> r[i]; } int zeros = 1000; while (zeros != 2) { zeros = 0; int nre = 0; for (int i = 1; i <= n; ++i) { if (l[i] == 0) ++zeros; if (r[i] == 0) ++zeros; if (l[i] == 0) { if (nre) { r[nre] = i; } l[i] = nre; nre = gre(i); } } } for (int i = 1; i <= n; ++i) { cout << l[i] << " " << r[i] << endl; } }
#include <bits/stdc++.h> using namespace std; int n, l[200], r[300], v[300]; int main() { cin >> n; for (int i = 1; i <= n; ++i) { cin >> l[i] >> r[i]; } int t = 0; for (int i = 1; i <= n; ++i) { if (l[i] == 0) { v[i] = t; int x = r[i]; while (x) { v[x] = t; x = r[x]; } ++t; } } for (int i = 1; i <= n && t > 1; ++i) { if (r[i] == 0) { for (int j = 1; j <= n; ++j) { if (i == j) continue; if (l[j] == 0 && v[i] != v[j]) { l[j] = i; r[i] = j; int x = v[i]; for (int a = 1; a <= n; ++a) if (v[a] == x) v[a] = v[j]; break; } } --t; } } for (int i = 1; i <= n; ++i) cout << l[i] << " " << r[i] << endl; return 0; }
#include <bits/stdc++.h> using namespace std; int l[105], r[105]; int num; int fa[105]; int Find(int k) { if (k == fa[k]) return k; else return fa[k] = Find(fa[k]); } int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; i++) fa[i] = i; for (int i = 1; i <= n; i++) { scanf("%d %d", &l[i], &r[i]); if (r[i] == 0) num++; if (l[i] != 0) fa[i] = l[i]; } for (int i = 1; i <= n; i++) { if (num == 1) break; if (r[i] == 0) { for (int j = 1; j <= n; j++) if (l[j] == 0 && Find(i) != j) { r[i] = j; l[j] = i; fa[j] = i; num--; break; } } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); }
#include <bits/stdc++.h> using namespace std; template <typename T> using vec = vector<T>; template <typename T> using pq = priority_queue<T, vector<T>, std::greater<T>>; template <typename T> using mxpq = priority_queue<T>; template <typename A, typename B> istream& operator>>(istream& s, pair<A, B>& p) { return s >> p.first >> p.second; } template <typename T> istream& operator>>(istream& s, vec<T>& p) { for (T& t : p) s >> t; return s; } struct uf { vec<long long> v; uf(int n) : v(n) { iota(v.begin(), v.end(), 0); } int find(int a) { if (v[a] == a) return a; v[a] = find(v[a]); return v[a]; } void u(int a, int b) { a = find(a), b = find(b); if (a == b) return; v[a] = b; } }; int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); int n; cin >> n; vec<long long> l0, r0; vec<pair<long long, long long>> p; uf u(n + 1); for (int i = (1); i < (n + 1); ++i) { int l, r; cin >> l >> r; p.emplace_back(l, r); if (l == 0) l0.push_back(i); else u.u(i, l); if (r == 0) r0.push_back(i); else u.u(i, r); } assert((int)(l0).size() == (int)(r0).size()); while ((int)(l0).size() > 1) { int l = l0.back(); l0.pop_back(); int r = r0.back(); if (u.find(l) == u.find(r)) r = r0[(int)(r0).size() - 2], r0.erase(r0.end() - 2); else r0.pop_back(); p[l - 1].first = r; p[r - 1].second = l; u.u(l, r); } for (auto& x : (p)) cout << x.first << " " << x.second << endl; }
#include <bits/stdc++.h> using namespace std; int l[100010], r[100010], vis[100010], n; int dfs(int rt) { if (r[rt] == 0) return rt; vis[rt] = 1; dfs(r[rt]); } pair<int, int> pp[100010]; int main() { scanf("%d", &n); for (int i = 1; i < (n + 1); i++) scanf("%d %d", &l[i], &r[i]); int cnt = 0; for (int i = 1; i <= n; i++) { if (l[i] == 0) { pp[++cnt].first = i; pp[cnt].second = dfs(i); } } if (cnt > 1) { r[pp[1].second] = pp[2].first; l[pp[2].first] = pp[1].second; for (int i = 2; i < cnt; i++) { r[pp[i].second] = pp[i + 1].first; l[pp[i + 1].first] = pp[i].second; } } for (int i = 1; i <= n; i++) cout << l[i] << " " << r[i] << endl; }
#include <bits/stdc++.h> using namespace std; long long const MAXN = 1e5 + 8; long long const INF = 1e12 + 8; long long const delta = 1000000007; int main() { std::ios::sync_with_stdio(0); ; cin.tie(0); cout.tie(0); long long n; cin >> n; long long l[n + 1], r[n + 1]; vector<long long> temp; long long last = -1; long long par; for (long long i = 1; i <= n; i++) { cin >> l[i] >> r[i]; if (last == -1 && r[i] == 0) { last = i; par = i; } } while (l[par]) par = l[par]; for (long long i = 1; i <= n; i++) { if (!l[i] && i != par) temp.push_back(i); ; } for (long long i = 0; i < temp.size(); i++) { l[temp[i]] = last; r[last] = temp[i]; last = temp[i]; while (r[last] != 0) { last = r[last]; } } for (long long i = 1; i <= n; i++) { cout << l[i] << " " << r[i] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; int n, cap[150], c, lst; pair<int, int> a[150], listt[150]; int main() { scanf("%d\n", &n); for (int i = 1; i <= n; ++i) { scanf("%d %d", &a[i].first, &a[i].second); if (!a[i].first) cap[++c] = i; } for (int i = 1; i <= c; ++i) { listt[++lst].first = cap[i]; int la = a[cap[i]].second; if (la == 0) listt[lst].second = cap[i]; while (la != 0) listt[lst].second = la, la = a[la].second; } for (int i = 1; i < lst; ++i) { a[listt[i].second].second = listt[i + 1].first; a[listt[i + 1].first].first = listt[i].second; } for (int i = 1; i <= n; ++i) printf("%d %d\n", a[i].first, a[i].second); return 0; }
#include <bits/stdc++.h> using namespace std; int p = 0, sum = 0; void BFS(vector<vector<int> > &v, int d, bool b[], int k) { int level[d + 1]; memset(level, -1, sizeof(level)); level[k] = 0; b[k] = true; list<int> q; q.push_back(k); while (!q.empty()) { int x = q.front(); q.pop_front(); vector<int>::iterator it; it = v[x].begin(); for (; it != v[x].end(); it++) { if (!b[*it]) { b[*it] = true; q.push_back(*it); level[*it] = level[x] + 1; if (*it == d) cout << level[*it] << '\n'; } } } } int main() { long long l, r, a, d, e, y, sum = 0, x1, y1, x2, y2, t, co = 0, n, n1, x, c = 0, m = 1000000007; float h = 0, su = 0, ans = 0; cin >> n; vector<pair<int, int> > v(n); vector<pair<int, int> > ve(n + 1); int g = 0; for (long long i = 0; i < n; i++) cin >> v[i].first >> v[i].second; set<int> s; set<int>::iterator it; for (long long i = 0; i < n; i++) s.insert(1 + i); bool b[n + 1]; for (long long i = 0; i < n + 1; i++) b[i] = false; b[0] = false; while (!s.empty()) { it = s.begin(); s.erase(it); int x = *it; list<int> l; l.push_back(x); while (!l.empty()) { x = l.front(); l.pop_front(); b[x] = true; s.erase(x); x--; if (b[v[x].first] == false) { if (v[x].first == 0) ve[g].first = x + 1; else l.push_back(v[x].first); } if (b[v[x].second] == false) { if (v[x].second == 0) ve[g].second = x + 1; else l.push_back(v[x].second); } } g++; } for (long long i = 0; i < g - 1; i++) v[ve[i].first - 1].first = ve[i + 1].second, v[ve[i + 1].second - 1].second = ve[i].first; for (long long i = 0; i < n; i++) cout << v[i].first << " " << v[i].second << '\n'; }
#include <bits/stdc++.h> using namespace std; void solve() { int n; cin >> n; vector<pair<int, int> > all; set<int> st; for (int i = 1; i <= n; i++) st.insert(i); for (int i = 0; i < n; i++) { int x, y; cin >> x >> y; all.emplace_back(x, y); if (st.count(x)) st.erase(x); if (st.count(y)) st.erase(y); } vector<int> fff; for (int i = 1; i <= n; i++) { bool f = 0; int cnt = 0; for (auto it : all) { if (it.first == i) { cnt++; f = 1; } if (it.second == i) { cnt++; } } if (cnt == 1 && f) { fff.push_back(i); } } for (auto it : st) fff.push_back(it); vector<int> v; v.push_back(0); for (auto out : fff) { v.push_back(out); while (all[out - 1].second != 0) { v.push_back(all[out - 1].second); out = all[out - 1].second; } } v.push_back(0); vector<pair<int, int> > ans(n); for (int i = 1; i + 1 < v.size(); i++) { ans[v[i] - 1] = {v[i - 1], v[i + 1]}; } for (auto it : ans) { cout << it.first << " " << it.second << "\n"; } } int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); int tc = 1; while (tc--) { solve(); } return 0; }
#include <bits/stdc++.h> using namespace std; vector<int> checked(101, 0); int cleared = 0; int findhead(vector<pair<int, int> >& allnodes) { int i = 1; for (i = 1; i < allnodes.size(); i++) { if (allnodes[i].first == 0 && checked[i] == 0) { return i; } } } int traverse(int i, vector<pair<int, int> >& allnodes) { if (allnodes[i].second == 0) { checked[i] = 1; cleared++; return i; } checked[i] = 1; cleared++; return traverse(allnodes[i].second, allnodes); } int main() { int n; cin >> n; vector<pair<int, int> > allnodes; pair<int, int> temp; temp.first = -2; temp.second = -2; allnodes.push_back(temp); int i, j; for (i = 0; i < n; i++) { cin >> temp.first >> temp.second; allnodes.push_back(temp); } int temphead = findhead(allnodes); int tail = traverse(temphead, allnodes); while (cleared != n) { temphead = findhead(allnodes); allnodes[tail].second = temphead; allnodes[temphead].first = tail; tail = traverse(temphead, allnodes); } for (i = 1; i <= n; i++) { cout << allnodes[i].first << " " << allnodes[i].second << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const long long mod = 1000000007; template <typename T> T gcd(T a, T b) { return b != 0 ? gcd(b, a % b) : a; } int main() { ios::sync_with_stdio(0), cin.tie(0); int n; cin >> n; map<int, int> l; map<int, int> r; vector<int> v; int a, b; for (int i = 1; i < n + 1; i++) { cin >> a >> b; l[i] = a; r[i] = b; if (a == 0) { v.push_back(i); } } priority_queue<pair<int, pair<int, int>>> pq; for (int i = 0; i < v.size(); i++) { int x = v[i]; while (r[x] != 0) { pq.push(make_pair(x, make_pair(l[x], r[x]))); x = r[x]; } if (i + 1 == v.size()) { pq.push(make_pair(x, make_pair(l[x], r[x]))); break; } r[x] = v[i + 1]; pq.push(make_pair(x, make_pair(l[x], r[x]))); l[v[i + 1]] = x; } vector<pair<int, int>> v1; while (!pq.empty()) { v1.push_back(make_pair(pq.top().second.first, pq.top().second.second)); pq.pop(); } for (int i = v1.size() - 1; i >= 0; i--) { cout << v1[i].first << " " << v1[i].second << "\n"; } return 0; }
#include <bits/stdc++.h> using namespace std; const int maxn = int(1e5) + 5; int l[maxn], r[maxn], P[maxn], sz[maxn]; inline int root(int x) { return (x == P[x]) ? x : (P[x] = root(P[x])); } void dsu(int x, int y) { x = root(x), y = root(y); if (sz[x] < sz[y]) swap(x, y); P[y] = x; sz[x] += sz[y]; } int main(void) { int n; scanf("%d", &n); set<int> strt, en; for (int i = 1; i <= n; i++) P[i] = i, sz[i] = -1; for (int i = 1; i <= n; i++) { scanf("%d%d", &l[i], &r[i]); if (!l[i]) strt.insert(i); else dsu(i, l[i]); if (!r[i]) en.insert(i); else dsu(i, r[i]); } while (int(strt.size()) > 1 && int(en.size()) > 1) { int x = *strt.begin(), y; for (auto it : en) { if (root(it) != root(x)) { y = it; break; } } en.erase(y), strt.erase(x); r[y] = x, l[x] = y; dsu(y, r[y]), dsu(x, l[x]); } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); }
#include <bits/stdc++.h> using namespace std; int n; const int maxn = 105; struct node { int l, r; void read() { cin >> l >> r; } } a[maxn]; int head[maxn], rear[maxn]; int tot; int main() { tot = 0; cin >> n; for (int i = 1; i <= n; i++) { scanf("%d%d", &a[i].l, &a[i].r); } for (int i = 1; i <= n; i++) { if (a[i].l == 0) { int j = i; while (a[j].r != 0) { j = a[j].r; } head[++tot] = i; rear[tot] = j; } } for (int i = 2; i <= tot; i++) { int u = rear[1], v = head[i]; a[u].r = v; a[v].l = u; rear[1] = rear[i]; } for (int i = 1; i <= n; i++) { printf("%d %d\n", a[i].l, a[i].r); } return 0; }
#include <bits/stdc++.h> using namespace std; int l[105]; int r[105]; int main() { int n; scanf("%d", &n); vector<int> left; vector<int> right; for (int i = 1; i <= n; i++) { scanf("%d%d", &l[i], &r[i]); if (l[i] == 0) { left.push_back(i); } if (r[i] == 0) { right.push_back(i); } } for (int i = 0; i < left.size() - 1; i++) { int shouldBeChangedLeft = left[i]; int inVaildRight = shouldBeChangedLeft; while (r[inVaildRight] != 0) { inVaildRight = r[inVaildRight]; } int chosenRight; for (int i = 1; i <= n; i++) { if (r[i] == 0 && i != inVaildRight) { chosenRight = i; break; } } l[shouldBeChangedLeft] = chosenRight; r[chosenRight] = shouldBeChangedLeft; } for (int i = 1; i <= n; i++) { printf("%d %d\n", l[i], r[i]); } return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; vector<pair<int, int> > p(n + 1); vector<bool> b(n + 1, false); for (int i = 1; i < n + 1; i++) cin >> p[i].first >> p[i].second; int z = 0; for (int i = 1; i < n + 1; i++) if (!b[i] && p[i].first == 0) { p[i].first = z; b[i] = true; p[z].second = i; z = i; while (p[z].second != 0) { b[z] = true; z = p[z].second; } } for (int i = 1; i < p.size(); i++) cout << p[i].first << ' ' << p[i].second << endl; }
#include <bits/stdc++.h> struct Node { int front; int next; } a[104]; int f[110]; void init(int n) { for (int i = 1; i <= n; i++) { f[i] = i; } return; } int getf(int v) { if (v == f[v]) return v; else { f[v] = getf(f[v]); return f[v]; } } int merge_f(int x, int y) { int t1 = getf(x); int t2 = getf(y); if (t1 != t2) { f[t2] = t1; return 1; } else { return 0; } } int main() { int n, i, j; while (~scanf("%d", &n)) { init(n); for (i = 1; i <= n; i++) { scanf("%d %d", &a[i].front, &a[i].next); if (a[i].front != 0) f[i] = a[i].front; } for (i = 1; i <= n; i++) { if (a[i].next != 0) continue; for (j = 1; j <= n; j++) { if (i != j && a[j].front == 0) { if (merge_f(i, j)) { a[i].next = j; a[j].front = i; break; } } } } for (i = 1; i <= n; i++) { printf("%d %d\n", a[i].front, a[i].next); } } return 0; }
#include <bits/stdc++.h> using namespace std; int prv[101]; int prox[101]; int group[101]; void setgroup(int i, int g) { while (prox[i] != 0) { group[i] = g; i = prox[i]; } group[i] = g; } int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { cin >> prv[i] >> prox[i]; } int curr = 1; memset(group, 0, sizeof(group)); for (int i = 1; i <= n; i++) { if (prv[i] == 0) { setgroup(i, curr); curr++; } } while (true) { int i; for (i = 1; i <= n; i++) { if (prv[i] == 0) break; } int j; for (j = 1; j <= n; j++) { if (prox[j] == 0 && group[j] != group[i]) { setgroup(i, group[j]); prox[j] = i; prv[i] = j; break; } } if (j > n) break; } for (int i = 1; i <= n; i++) { cout << prv[i] << " " << prox[i] << endl; } }
#include <bits/stdc++.h> using namespace std; const int MAXN = 2e2 + 10; int n; int li[MAXN]; int ri[MAXN]; int fa[MAXN]; void init(int n) { for (int i = 1; i <= n; ++i) fa[i] = i; } int find(int a) { if (fa[a] != a) return fa[a] = find(fa[a]); return fa[a]; } void un(int a, int b) { a = find(a); b = find(b); if (a == b) return; fa[a] = b; } int main() { while (cin >> n) { int tn = 0; init(n); for (int i = 1; i <= n; ++i) cin >> li[i] >> ri[i]; for (int i = 1; i <= n; ++i) { if (li[i]) un(i, li[i]); if (ri[i]) un(i, ri[i]); if (!ri[i]) ++tn; } for (int i = 1; i <= n && tn > 1; ++i) { if (ri[i] == 0) { for (int j = 1; j <= n; ++j) { if (li[j] == 0 && find(j) != find(i)) { ri[i] = j; li[j] = i; un(i, j); --tn; break; } } } } for (int i = 1; i <= n; ++i) { cout << li[i] << " " << ri[i] << endl; } } return 0; }
#include <bits/stdc++.h> using namespace std; int n, sum; int a[1000][2], fa[1000]; int getfa(int x) { return x == fa[x] ? x : fa[x] = getfa(fa[x]); } int main() { scanf("%d", &n); sum = n; for (int i = 1; i <= n; i++) fa[i] = i; for (int i = 1; i <= n; i++) { scanf("%d %d", &a[i][0], &a[i][1]); if (a[i][0]) { if (getfa(a[i][0]) != getfa(i)) sum--, fa[fa[i]] = fa[a[i][0]]; } if (a[i][1]) { if (getfa(a[i][1]) != getfa(i)) sum--, fa[fa[i]] = fa[a[i][1]]; } } while (sum != 1) { sum--; bool bz = 0; for (int i = 1; i <= n && !bz; i++) for (int j = 1; j <= n && !bz; j++) if (getfa(i) != getfa(j) && !a[i][1] && !a[j][0]) { a[i][1] = j, a[j][0] = i; fa[fa[i]] = fa[j]; bz = 1; } } for (int i = 1; i <= n; i++) printf("%d %d\n", a[i][0], a[i][1]); return 0; }
#include <bits/stdc++.h> using namespace std; struct node { int pred; int info; int next; node(int a = 0, int b = 0, int c = 0) : pred(a), info(b), next(c) {} }; int main() { node a[101]; int n, pr, nx; cin >> n; int c = 0; int b[101] = {0}; for (int i = 1; i <= n; i++) { cin >> pr >> nx; a[i] = node(pr, i, nx); if (pr == 0) { b[c] = i; c++; } } vector<node> list; for (int i = 0; i < c; i++) { if (list.empty()) { list.push_back(a[b[i]]); } else { int t = list[list.size() - 1].info; a[t].next = a[b[i]].info; a[b[i]].pred = t; list.push_back(a[b[i]]); } while (list[list.size() - 1].next != 0) { list.push_back(a[list[list.size() - 1].next]); } } for (int i = 1; i <= n; i++) { cout << a[i].pred << " " << a[i].next << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; const double PI = acos(-1.0); inline int getint() { int x; scanf("%d", &x); return x; } inline long long getlng() { long long x; scanf("%lld", &x); return x; } int dx4[] = {-1, 0, 1, 0}; int dy4[] = {0, 1, 0, -1}; int dx8[] = {-1, -1, -1, 0, 0, 1, 1, 1}; int dy8[] = {-1, 0, 1, -1, 1, -1, 0, 1}; const int N = 110; pair<int, int> P[N]; bool mark[N]; int n; vector<int> v; vector<vector<int> > chains; int main() { memset(P, -1, sizeof P); ; memset(mark, false, sizeof mark); ; cin >> n; for (int i = 1; i <= n; ++i) { cin >> P[i].first >> P[i].second; if (P[i].first == 0 && P[i].second == 0) { chains.push_back(vector<int>(1, i)); mark[i] = true; } } for (int i = 1; i <= n; ++i) { if (mark[i]) continue; if (P[i].first == 0 && P[i].second > 0) { vector<int> nv; nv.push_back(i); mark[i] = true; int curr = P[i].second; while (curr > 0) { nv.push_back(curr); mark[curr] = true; curr = P[curr].second; } chains.push_back(nv); } } for (int i = 1; i <= n; ++i) { if (mark[i]) continue; if (P[i].first > 0 && P[i].second == 0) { vector<int> nv; nv.push_back(i); mark[i] = true; int curr = P[i].first; while (curr > 0) { nv.push_back(curr); mark[curr] = true; curr = P[curr].first; } reverse(nv.begin(), nv.end()); chains.push_back(nv); } } for (int i = 0; i < chains.size(); ++i) { for (const auto& x : chains[i]) { v.push_back(x); } } if (n == 1) { printf("0 0\n"); return 0; } for (int i = 1; i <= n; ++i) { int it = -1; for (int j = 0; j < ((int)v.size()); ++j) { if (v[j] == i) { it = j; break; } } if (it == 0) { printf("0 %d\n", v[it + 1]); } else if (it + 1 == ((int)v.size())) { printf("%d 0\n", v[it - 1]); } else { printf("%d %d\n", v[it - 1], v[it + 1]); } } return 0; }
#include <bits/stdc++.h> using namespace std; int l[105], r[105]; int n; bool used; inline int find(int now) { if (!r[now]) return now; return find(r[now]); } int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]); for (int i = 1; i <= n; i++) if (!l[i]) { if (!used) { used = 1; continue; } for (int j = 1; j <= n; j++) if (j != i && !r[j] && find(r[i]) != j) { r[j] = i, l[i] = j; break; }; } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int INF = 1e9; const int N = 100; int l[N + 1]; int r[N + 1]; int main() { ios_base::sync_with_stdio(0); int n; cin >> n; vector<int> begins; for (int i = 1; i <= n; ++i) { cin >> l[i] >> r[i]; if (l[i] == 0) { begins.push_back(i); } } vector<pair<int, int> > q; for (auto i : begins) { int a = i; int b = i; while (r[b] != 0) { b = r[b]; } q.push_back({a, b}); } while (q.size() > 1) { int a = q.back().first; int b = q.back().second; q.pop_back(); int c = q.back().first; int d = q.back().second; q.pop_back(); r[b] = c; l[c] = b; q.push_back({a, d}); } for (int i = 1; i <= n; ++i) { cout << l[i] << " " << r[i] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; int main() { std::ios::sync_with_stdio(0); cin.tie(0); long long n; cin >> n; vector<pair<long long, long long> > a(n + 5, {0, 0}); set<long long> l, r; for (long long i = 1; i <= n; i++) { cin >> a[i].first >> a[i].second; if (!a[i].first) l.insert(i); if (!a[i].second) r.insert(i); } for (long long i = 1; i <= n; i++) { if (l.size() == 1 and r.size() == 1) break; long long left = *l.begin(), right, right_end = left; while (a[right_end].second) right_end = a[right_end].second; for (auto it : r) { if (it == left or it == right_end) continue; right = it; break; } l.erase(left); r.erase(right); a[left].first = right, a[right].second = left; } for (long long i = 1; i <= n; i++) cout << a[i].first << " " << a[i].second << "\n"; }
#include <bits/stdc++.h> using namespace std; int n; int l[100 + 5]; int r[100 + 5]; int par[105]; int get_most_left(int i) { if (l[i] == 0) { return i; } par[i] = get_most_left(l[i]); return par[i]; } bool one_linked_list() { set<int> parents; memset(par, -1, sizeof(par)); for (int i = 1; i <= n; i++) { if (par[i] == -1) { parents.insert(get_most_left(i)); } } if (parents.size() == 1) return true; return false; } int main() { memset(par, -1, sizeof(par)); scanf("%d", &n); for (int i = 1; i <= n; i++) { scanf("%d %d", &l[i], &r[i]); } while (!one_linked_list()) { for (int i = 1; i <= n; i++) { if (r[i] == 0) { for (int j = 1; j <= n; j++) { if (i != j && l[j] == 0 && get_most_left(i) != get_most_left(j) && (r[i] != l[j] || (r[i] == 0 && l[j] == 0))) { r[i] = j; l[j] = i; break; } } } } } for (int i = 1; i <= n; i++) { printf("%d %d\n", l[i], r[i]); } return 0; }
#include <bits/stdc++.h> using namespace std; const int MaxN = 103; int n; int l[MaxN], r[MaxN]; int main() { scanf("%d", &n); for (int i = 1; i <= n; ++i) scanf("%d%d", l + i, r + i); int last = 0; for (int i = 1; i <= n; ++i) if (l[i] == 0) { r[last] = i; l[i] = last; int p = i; while (r[p]) p = r[p]; last = p; } for (int i = 1; i <= n; ++i) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int N = 105; int n; int l[N], r[N]; int main() { scanf("%d", &n); vector<int> roots; for (int i = 1; i <= n; i++) { scanf("%d%d", l + i, r + i); if (l[i] == 0) roots.push_back(i); } int prv; while (true) { prv = roots.back(); roots.pop_back(); for (int i = r[prv]; i; i = r[i]) { r[prv] = i; prv = i; } if (!roots.empty()) { r[prv] = roots.back(); l[roots.back()] = prv; } else { break; } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; int main() { long long n; cin >> n; int l[n], r[n]; int op = 0; for (int i = 0; i < n; i++) { cin >> l[i] >> r[i]; } int left = -1, right = -1; for (int i = 0; i < n; i++) { if (l[i] == 0) { if (left == -1 && right == -1) { left = i + 1; right = i + 1; while (r[right - 1] != 0) { right = r[right - 1]; } } else { l[i] = right; r[right - 1] = i + 1; right = i + 1; while (r[right - 1] != 0) { right = r[right - 1]; } } } } for (int i = 0; i < n; i++) { cout << l[i] << " " << r[i] << "\n"; } return 0; }
#include <bits/stdc++.h> using namespace std; vector<int> in[105], out[105]; int vis[105]; int main() { int n, d; cin >> n; pair<int, int> ara[n + 1]; for (int i = 1; i <= n; i++) { scanf("%d %d", &ara[i].first, &ara[i].second); in[ara[i].first].push_back(i); out[ara[i].second].push_back(i); } int idx = in[0].back(); vis[idx] = 1; while (1) { int f = 0; for (int i = 1; i <= n; i++) if (vis[i] == 1) f = 1; if (f == 0) break; while (ara[idx].second != 0) idx = ara[idx].second, vis[idx] = 1; while (in[0].empty() == 0 && vis[in[0].back()] == 1) in[0].pop_back(); if (in[0].empty()) break; ara[idx].second = in[0].back(); ara[in[0].back()].first = idx; } for (int i = 1; i <= n; i++) printf("%d %d\n", ara[i].first, ara[i].second); return 0; }
#include <bits/stdc++.h> using namespace std; struct node { int id, left, right; node(int i = 0, int l = 0, int r = 0) : id(i), left(l), right(r){}; }; int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); int n; cin >> n; vector<node> v(n); for (int i = 1; i <= n; ++i) { v[i - 1].id = i; cin >> v[i - 1].left >> v[i - 1].right; } vector<vector<node>> lists; for (int i = 0; i < n; ++i) { if (v[i].left == 0) { int j = i; vector<node> list; list.push_back(v[j]); while (v[j].right) { list.push_back(v[v[j].right - 1]); j = v[j].right - 1; } lists.push_back(list); } } for (int i = 0; i < lists.size() - 1; ++i) { int list_size = lists[i].size(); lists[i][list_size - 1].right = lists[i + 1][0].id; lists[i + 1][0].left = lists[i][list_size - 1].id; } for (auto& list : lists) { for (auto& i : list) { v[i.id - 1].left = i.left; v[i.id - 1].right = i.right; } } for (auto& i : v) { cout << i.left << " " << i.right << endl; } }
#include <bits/stdc++.h> int l[101]; int r[101]; int end(int x) { while (r[x]) x = r[x]; return x; } int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; i++) { scanf("%d%d", l + i, r + i); } int p = 0; for (int i = 1; i <= n; i++) { if (l[i] == 0) { int x = end(i); if (p != 0) { l[i] = p; r[p] = i; } p = x; } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> int n; int list[102][2]; int lempty[102], lsz; int rempty[102], rsz; int no[102]; bool vis[102]; bool vis_r[102]; int first, last; int main() { scanf("%d", &n); int a, b; for (int i = 1; i <= n; i++) { scanf("%d %d", &a, &b); list[i][0] = a; list[i][1] = b; if (list[i][0] == 0) lempty[lsz++] = i; if (list[i][1] == 0) rempty[rsz++] = i; } int c = 1; for (int i = 1; i <= n; i++) { if (!vis[i]) { vis[i] = true; no[i] = c; int l = list[i][0]; while (l != 0) { vis[l] = true; no[l] = c; l = list[l][0]; } int r = list[i][1]; while (r != 0) { vis[r] = true; no[r] = c; r = list[r][0]; } c++; } } for (int i = 0; i < lsz - 1; i++) { for (int j = 0; j < rsz; j++) { if (vis_r[j]) continue; if (no[rempty[j]] != no[lempty[i]]) { list[lempty[i]][0] = rempty[j]; list[rempty[j]][1] = lempty[i]; int r = lempty[i]; int k = no[rempty[j]]; while (r != 0) { no[r] = k; r = list[r][1]; } vis_r[j] = true; break; } } } for (int i = 1; i <= n; i++) { printf("%d %d\n", list[i][0], list[i][1]); } return 0; }
#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; int left[n + 1]; int right[n + 1]; bool visited[n + 1]; vector<int> left_indices; vector<int> right_indices; int i; for (i = 1; i <= n; i++) { left[i] = 0; right[i] = 0; visited[i] = 0; } for (i = 1; i <= n; i++) cin >> left[i] >> right[i]; for (i = 1; i <= n; i++) { if (visited[i] == 0) { queue<int> q; q.push(i); visited[i] = 1; while (!q.empty()) { int curr = q.front(); visited[curr] = 1; if (left[curr] == 0) left_indices.push_back(curr); else { if (visited[left[curr]] == 0) q.push(left[curr]); } if (right[curr] == 0) right_indices.push_back(curr); else { if (visited[right[curr]] == 0) q.push(right[curr]); } q.pop(); } } } for (i = 0; i < right_indices.size() - 1; i++) { right[right_indices[i]] = left_indices[i + 1]; } for (i = 1; i < left_indices.size(); i++) { left[left_indices[i]] = right_indices[i - 1]; } for (i = 1; i <= n; i++) cout << left[i] << " " << right[i] << "\n"; }
#include <bits/stdc++.h> using namespace std; int l[107]; int r[107]; bool vis[107]; vector<pair<int, int> > Lists; int main() { int i, j, k, m, n, x, y, z, a, b; scanf("%d", &n); for (i = 1; i <= n; i++) { scanf("%d", &l[i]); scanf("%d", &r[i]); } for (i = 1; i <= n; i++) { if (!vis[i]) { j = i; while (l[j] != 0) vis[j] = true, j = l[j]; a = j; vis[a] = true; j = i; while (r[j] != 0) vis[j] = true, j = r[j]; b = j; vis[b] = true; Lists.push_back(make_pair(a, b)); } } for (i = 1; i < (int)Lists.size(); i++) { l[Lists[i].first] = Lists[i - 1].second; r[Lists[i - 1].second] = Lists[i].first; } for (i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; int left_[105], right_[105], mark[105]; int main() { int n, j; std::ios::sync_with_stdio(0); while (~scanf("%d", &n)) { int ans = 0; memset(left_, 0, sizeof(left_)); memset(right_, 0, sizeof(right_)); memset(mark, 0, sizeof(mark)); for (int i = 1; i <= n; i++) { scanf("%d %d", &left_[i], &right_[i]); if (left_[i] == 0) mark[++ans] = i; } for (int i = 1; i < ans; i++) { for (j = mark[i]; right_[j] != 0; j = right_[j]) ; left_[mark[i + 1]] = j; right_[j] = mark[i + 1]; } for (int i = 1; i <= n; i++) printf("%d %d\n", left_[i], right_[i]); } }
#include <bits/stdc++.h> using namespace std; int l[110], r[110]; int par[110]; void init(int n) { for (int i = 0; i < int(n); i++) { par[i + 1] = i + 1; } } int find(int x) { if (par[x] == x) { return x; } else { return par[x] = find(par[x]); } } void unite(int x, int y) { x = find(x); y = find(y); if (x == y) return; par[x] = y; } bool same(int x, int y) { return find(x) == find(y); } int main(void) { int i, j, k; cin.tie(0); ios_base::sync_with_stdio(false); int n; cin >> n; init(n); for (i = 1; i <= n; i++) { int x, y; cin >> x >> y; l[i] = x; r[i] = y; if (x != 0) unite(x, i); if (y != 0) unite(y, i); } int mx = 0; for (i = 1; i <= n; i++) { par[i] = find(i); mx = max(mx, par[i]); } for (i = 1; i < mx; i++) { int x, y; bool f = false; for (j = 1; j <= n; j++) { if (find(j) == i) { if (r[j] == 0) { x = j; f = true; break; } } } if (!f) continue; bool g = false; for (j = 1; j <= n; j++) { if (find(j) != i) { if (l[j] == 0) { y = j; g = true; break; } } } if (!g) continue; r[x] = y; l[y] = x; unite(x, y); } for (i = 1; i <= n; i++) { cout << l[i] << ' ' << r[i] << endl; } return 0; }
#include <bits/stdc++.h> using namespace std; int L[(110)], R[(110)]; int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; ++i) scanf("%d %d\n", &L[i], &R[i]); int pre = 0; for (int i = 1; i <= n; ++i) if (L[i] == 0) { L[i] = pre; R[pre] = i; int w = R[i]; for (; R[w]; w = R[w]) ; pre = w; } for (int i = 1; i <= n; ++i) printf("%d %d\n", L[i], R[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const int N = 105; int l[N]; int r[N]; int visited[N]; int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { scanf("%d %d", l + i, r + i); } int prevEndNode = 0; for (int i = 1; i <= n; i++) { if (!visited[i]) { visited[i] = 1; int startNode = i; while (l[startNode]) { startNode = l[startNode]; visited[startNode] = 1; } int endNode = i; while (r[endNode]) { endNode = r[endNode]; visited[endNode] = 1; } if (prevEndNode) { l[startNode] = prevEndNode; r[prevEndNode] = startNode; } prevEndNode = endNode; } } for (int i = 1; i <= n; i++) { printf("%d %d\n", l[i], r[i]); } }
#include <bits/stdc++.h> using namespace std; int n, l[505], r[505], cnt = 0; inline bool checkl(int x, int y) { if (l[x] == 0) return 1; else if (l[x] == y) return 0; return checkl(l[x], y); } inline bool checkr(int x, int y) { if (r[x] == 0) return 1; else if (r[x] == y) return 0; return checkr(r[x], y); } int main() { scanf("%d", &n); for (int i = 1; i <= n; i++) { scanf("%d%d", &l[i], &r[i]); if (l[i] == 0) cnt++; } for (int i = 1; i <= n; i++) { if (l[i] == 0 && cnt > 1) for (int j = 1; j <= n; j++) if (r[j] == 0 && i != j && checkr(i, j)) { r[j] = i; l[i] = j; cnt--; break; } if (r[i] == 0 && cnt > 1) for (int j = 1; j <= n; j++) if (l[j] == 0 && i != j && checkl(i, j) && checkr(i, j)) { l[j] = i; r[i] = j; cnt--; break; } } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }
#include <bits/stdc++.h> using namespace std; const long long oo = 0x3f3f3f3f3f3f3f3f; const double eps = 1e-9; int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); long long n; cin >> n; vector<long long> l(n), r(n); for (long long i = (0); i < (n); i++) cin >> l[i] >> r[i], l[i]--, r[i]--; vector<long long> c(n, -1); long long C = 0; for (long long i = (0); i < (n); i++) if (c[i] == -1) { c[i] = C; for (long long j = l[i]; j != -1; j = l[j]) c[j] = C; for (long long j = r[i]; j != -1; j = r[j]) c[j] = C; C++; } for (long long i = (0); i < (n); i++) if (r[i] == -1) for (long long j = (0); j < (n); j++) if (l[j] == -1) if (c[i] == c[j] + 1) r[i] = j, l[j] = i; for (long long i = (0); i < (n); i++) cout << l[i] + 1 << " " << r[i] + 1 << endl; }
#include <bits/stdc++.h> using namespace std; const int INF = 0x3f3f3f3f; const long long INFF = 0x3f3f3f3f3f3f3f3f; const double pi = acos(-1.0); const double eps = 1e-9; const long long mod = 1e9 + 7; int read() { int x = 0, f = 1; char ch = getchar(); while (ch<'0' | ch> '9') { if (ch == '-') f = -1; ch = getchar(); } while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); } return x * f; } void Out(int aa) { if (aa > 9) Out(aa / 10); putchar(aa % 10 + '0'); } vector<int> pl, pr, p0; int l[110], r[110]; int main() { int n = read(); for (int i = 1; i <= n; i++) { l[i] = read(), r[i] = read(); } int keep = 0; for (int i = 1; i <= n; i++) { if (!l[i]) { int j = i; for (; r[j]; j = r[j]) ; if (keep == 0) keep = j; else { l[i] = keep; r[keep] = i; keep = j; } } } for (int i = 1; i <= n; i++) { printf("%d %d\n", l[i], r[i]); } return 0; }
#include <bits/stdc++.h> using namespace std; template <typename T, typename U> inline void chkmax(T& x, U y) { if (x < y) x = y; } template <typename T, typename U> inline void chkmin(T& x, U y) { if (y < x) x = y; } int l[111], r[111]; int main() { int n; scanf("%d", &n); for (int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]); vector<int> V; V.push_back(0); for (int i = 1; i <= n; i++) if (!l[i]) { V.push_back(i); int j = i; while (r[j]) j = r[j]; V.push_back(j); } V.push_back(0); for (int i = 1; i < ((int)(V.size())) - 1; i++) { if (~i & 1) r[V[i]] = V[i + 1]; else l[V[i]] = V[i - 1]; } for (int i = 1; i <= n; i++) printf("%d %d\n", l[i], r[i]); return 0; }