Submission #994165

#	Time	Username	Problem	Language	Result	Execution time	Memory
994165		vjudge1	Jail (JOI22_jail)	C++17	0 / 100	7 ms	9048 KiB

jail

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int MAXN = 120'001;

vector<int> g[MAXN], g2[MAXN];
int tin[MAXN], tout[MAXN], s[MAXN], e[MAXN], par[MAXN], col[MAXN], timer;
bool ok;

void dfs(int u, int p = -1) {
    tin[u] = timer++;
    par[u] = p;
    for (int v : g[u]) {
        if (v != p) dfs(v, u);
    }
    tout[u] = timer++;
}

void dfs2(int u) {
    col[u] = 1;
    for (int v : g2[u]) {
        if (col[v] == 0) dfs2(v);
        else if (col[v] == 1) ok = false;
    }
    col[u] = 2;
}

bool is_ancestor(int u, int v) {
    return tin[u] <= tin[v] && tout[v] <= tout[u];
}

void solve() {
    int n; cin >> n;
    ok = true;
    fill(s, s+n+1, 0);
    fill(e, e+n+1, 0);
    fill(col, col+n+1, 0);
    timer = 1;
    for (int i = 1; i <= n; i++) {
        g[i].clear();
        g2[i].clear();
    }
    for (int i = 0; i < n-1; i++) {
        int u, v; cin >> u >> v;
        g[u].emplace_back(v);
        g[v].emplace_back(u);
    }
    dfs(1);
    int m; cin >> m;
    vector<pair<int, int>> edges(m+1);
    for (int i = 1; i <= m; i++) {
        cin >> edges[i].first >> edges[i].second;
        auto [u, v] = edges[i];
        s[u] = e[v] = i;
    }

    auto nxt = [&](int u, int v) {
        if (u == v) return -1;
        if (is_ancestor(u, v)) {
            for (int i : g[u]) {
                if (par[u] != i && is_ancestor(i, v)) {
                    return i;
                }
            }
        } else {
            return par[u];
        }
    };

    for (int i = 1; i <= m; i++) {
        auto [u, v] = edges[i];
        while (u != -1) {
            if (e[u] && e[u] != i) {
                g2[i].emplace_back(e[u]);
            }
            u = nxt(u, v);
        }
    }

    for (int i = 1; i <= m; i++) {
        if (col[i] == 0) dfs2(i);
    }
    cout << (ok?"Yes\n":"No\n");
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int t; cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}

Compilation message (stderr)

jail.cpp: In lambda function:
jail.cpp:70:5: warning: control reaches end of non-void function [-Wreturn-type]
   70 |     };
      |     ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 16
• Subtask 4: 0 / 28
• Subtask 5: 0 / 12
• Subtask 6: 0 / 11
• Subtask 7: 0 / 23