File size: 3,927 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 | #include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
if (!(cin >> n >> m)) return 0;
vector<int> a(10);
for (int i = 0; i < 10; ++i) cin >> a[i]; // scoring parameters, unused
vector<vector<int>> g(n + 1), rg(n + 1);
g.reserve(n + 1);
rg.reserve(n + 1);
for (int i = 0; i < m; ++i) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
rg[v].push_back(u);
}
for (int i = 1; i <= n; ++i) {
sort(g[i].begin(), g[i].end());
sort(rg[i].begin(), rg[i].end());
}
auto hasEdge = [&](int u, int v) -> bool {
const auto &gu = g[u];
return binary_search(gu.begin(), gu.end(), v);
};
vector<int> nxt(n + 1, 0), prv(n + 1, 0);
vector<char> inP(n + 1, 0);
// Random order
vector<int> order(n);
iota(order.begin(), order.end(), 1);
uint64_t seed = chrono::high_resolution_clock::now().time_since_epoch().count();
shuffle(order.begin(), order.end(), mt19937_64(seed));
int head = 0, tail = 0;
auto insert_between = [&](int u, int v, int w) {
// u -> v -> w
nxt[u] = v;
prv[v] = u;
nxt[v] = w;
prv[w] = v;
inP[v] = 1;
};
auto try_insert = [&](int v) -> bool {
if (inP[v]) return false;
if (head == 0) {
head = tail = v;
inP[v] = 1;
nxt[v] = prv[v] = 0;
return true;
}
// append
if (hasEdge(tail, v)) {
nxt[tail] = v;
prv[v] = tail;
nxt[v] = 0;
tail = v;
inP[v] = 1;
return true;
}
// prepend
if (hasEdge(v, head)) {
prv[head] = v;
nxt[v] = head;
prv[v] = 0;
head = v;
inP[v] = 1;
return true;
}
// try insert using outgoing edges v -> w (w in path), need prev[w] -> v
const auto &out = g[v];
for (int w : out) {
if (!inP[w]) continue;
int u = prv[w];
if (u == 0) continue; // w is head; prepend already checked
if (hasEdge(u, v)) {
insert_between(u, v, w);
return true;
}
}
// try insert using incoming edges u -> v (u in path), need v -> next[u]
const auto &in = rg[v];
for (int u : in) {
if (!inP[u]) continue;
int w = nxt[u];
if (w == 0) continue; // u is tail; append already checked
if (hasEdge(v, w)) {
insert_between(u, v, w);
return true;
}
}
return false;
};
// Build initial path
head = tail = order[0];
inP[head] = 1;
prv[head] = nxt[head] = 0;
vector<int> remain;
remain.reserve(n);
for (int i = 1; i < n; ++i) remain.push_back(order[i]);
// Perform a few passes to try to insert remaining vertices
int max_passes = 3;
for (int pass = 0; pass < max_passes && !remain.empty(); ++pass) {
shuffle(remain.begin(), remain.end(), mt19937_64(seed + pass + 1));
vector<int> nextRemain;
nextRemain.reserve(remain.size());
int insertedThisPass = 0;
for (int v : remain) {
if (inP[v]) continue;
if (!try_insert(v)) {
nextRemain.push_back(v);
} else {
insertedThisPass++;
}
}
remain.swap(nextRemain);
if (insertedThisPass == 0) break;
}
// Output result
vector<int> path;
path.reserve(n);
for (int x = head; x != 0; x = nxt[x]) path.push_back(x);
cout << (int)path.size() << "\n";
for (int i = 0; i < (int)path.size(); ++i) {
if (i) cout << ' ';
cout << path[i];
}
cout << "\n";
return 0;
} |