# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
557587 | DanShaders | Jail (JOI22_jail) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
namespace x = __gnu_pbds;
template <typename T>
using ordered_set = x::tree<T, x::null_type, less<T>, x::rb_tree_tag, x::tree_order_statistics_node_update>;
template <typename T>
using normal_queue = priority_queue<T, vector<T>, greater<>>;
#define all(x) begin(x), end(x)
#define sz(x) ((int) (x).size())
#define x first
#define y second
using ll = long long;
using ld = long double;
const int N = 1.25e5, M = 5 * N;
int s[N], t[N];
vector<int> g[N], g2[M];
char used[N];
vector<int> path;
bool dfs_cycle(int u) {
if (used[u] == 1) {
return false;
}
used[u] = 1;
for (int v : g2[u]) {
if (used[v] != 2 && !dfs_cycle(v)) {
return false;
}
}
used[u] = 2;
return true;
}
bool dfs(int u, int w, int p = -1) {
path.push_back(u);
if (u == w) {
return true;
}
for (int v : g[u]) {
if (v != p && dfs(v, w, u)) {
return true;
}
}
path.pop_back();
return false;
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
int testcases;
cin >> testcases;
while (testcases--) {
int n, m;
cin >> n;
for (int i = 0; i < 5 * n; ++i) {
g2[i].clear();
}
for (int i = 0; i < n; ++i) {
g[i].clear();
paths[i].clear();
}
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
g[--u].push_back(--v);
g[v].push_back(u);
}
cin >> m;
for (int i = 0; i < m; ++i) {
cin >> s[i] >> t[i];
--s[i], --t[i];
path.clear();
dfs(s[i], t[i]);
for (int u : path) {
if (u != s[i]) {
g2[4 * n + i].push_back(n + u);
}
}
for (int u : path) {
if (u != t[i]) {
g2[3 * n + u].push_back(4 * n + i);
}
}
g2[n + s[i]].push_back(4 * n + i);
g2[4 * n + i].push_back(3 * n + t[i]);
}
// for (int i = 0; i < 5 * n; ++i) {
// for (int v : g[i]) {
// cout << i << " -> " << v << endl;
// }
// }
fill(used, used + 5 * n, 0);
bool flag = true;
for (int i = 0; i < 5 * n; ++i) {
if (!used[i]) {
flag &= dfs_cycle(i);
}
}
cout << (flag ? "Yes\n" : "No\n");
}
}