File size: 4,206 Bytes
1fd0050 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 | #include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(NULL);
int n, m;
cin >> n >> m;
vector<int> a(10);
for (int i = 0; i < 10; i++) cin >> a[i];
vector<vector<int>> adj(n + 1), rev(n + 1);
for (int i = 0; i < m; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
rev[v].push_back(u);
}
vector<int> outdeg(n + 1);
for (int i = 1; i <= n; i++) outdeg[i] = adj[i].size();
for (int i = 1; i <= n; i++) {
sort(adj[i].begin(), adj[i].end(), [&](int x, int y) {
if (outdeg[x] != outdeg[y]) return outdeg[x] < outdeg[y];
return x < y;
});
}
vector<bool> vis(n + 1, false);
stack<int> order;
function<void(int)> dfs1 = [&](int u) {
vis[u] = true;
for (int v : adj[u]) if (!vis[v]) dfs1(v);
order.push(u);
};
for (int i = 1; i <= n; i++) if (!vis[i]) dfs1(i);
fill(vis.begin(), vis.end(), false);
vector<int> scc(n + 1, -1);
int scc_cnt = 0;
function<void(int, int)> dfs2 = [&](int u, int id) {
vis[u] = true;
scc[u] = id;
for (int v : rev[u]) if (!vis[v]) dfs2(v, id);
};
while (!order.empty()) {
int u = order.top(); order.pop();
if (!vis[u]) {
dfs2(u, scc_cnt);
scc_cnt++;
}
}
vector<int> scc_size(scc_cnt, 0);
for (int i = 1; i <= n; i++) scc_size[scc[i]]++;
vector<set<int>> dag_set(scc_cnt);
for (int u = 1; u <= n; u++) {
int s1 = scc[u];
for (int v : adj[u]) {
int s2 = scc[v];
if (s1 != s2) {
dag_set[s1].insert(s2);
}
}
}
vector<vector<int>> dag(scc_cnt);
vector<int> dag_indeg(scc_cnt, 0);
for (int i = 0; i < scc_cnt; i++) {
for (int j : dag_set[i]) {
dag[i].push_back(j);
dag_indeg[j]++;
}
}
queue<int> q;
vector<int> temp_indeg = dag_indeg;
vector<int> topo;
for (int i = 0; i < scc_cnt; i++) if (temp_indeg[i] == 0) q.push(i);
while (!q.empty()) {
int i = q.front(); q.pop();
topo.push_back(i);
for (int j : dag[i]) {
temp_indeg[j]--;
if (temp_indeg[j] == 0) q.push(j);
}
}
vector<long long> reach_size(scc_cnt, 0);
for (int idx = topo.size() - 1; idx >= 0; idx--) {
int i = topo[idx];
reach_size[i] = scc_size[i];
for (int j : dag[i]) {
reach_size[i] += reach_size[j];
}
}
vector<int> candidates;
for (int i = 1; i <= n; i++) {
if (reach_size[scc[i]] == n) {
candidates.push_back(i);
}
}
sort(candidates.begin(), candidates.end(), [&](int x, int y) {
if (outdeg[x] != outdeg[y]) return outdeg[x] < outdeg[y];
return x < y;
});
vector<char> visited(n + 1, 0);
vector<int> path;
function<bool(int, int)> dfs = [&](int u, int count) -> bool {
path.push_back(u);
visited[u] = 1;
bool res = (count == n);
if (!res) {
for (int v : adj[u]) {
if (visited[v] == 0) {
if (dfs(v, count + 1)) {
res = true;
break;
}
}
}
}
if (!res) {
path.pop_back();
visited[u] = 0;
}
return res;
};
vector<int> the_path;
bool found_ham = false;
for (int start : candidates) {
fill(visited.begin(), visited.end(), 0);
path.clear();
if (dfs(start, 1)) {
the_path = path;
found_ham = true;
break;
}
}
if (found_ham && the_path.size() == static_cast<size_t>(n)) {
cout << n << '\n';
for (size_t i = 0; i < the_path.size(); i++) {
cout << the_path[i];
if (i + 1 < the_path.size()) cout << " ";
else cout << '\n';
}
} else {
int some = 1;
if (!candidates.empty()) some = candidates[0];
cout << 1 << '\n' << some << '\n';
}
return 0;
} |