Submission #1164965

#	Time	Username	Problem	Language	Result	Execution time	Memory
1164965		jj_master	Jail (JOI22_jail)	C++20	0 / 100	1 ms	2632 KiB

jail

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 100005;

vector<int> adj[MAXN];
int depth[MAXN];
int parent[MAXN][20];
int n, m;

void dfs(int u, int p) {
    depth[u] = depth[p] + 1;
    parent[u][0] = p;
    for (int i = 1; i < 20; i++) {
        parent[u][i] = parent[parent[u][i - 1]][i - 1];
    }
    for (int v : adj[u]) {
        if (v != p) {
            dfs(v, u);
        }
    }
}

int lca(int u, int v) {
    if (depth[u] < depth[v]) {
        swap(u, v);
    }
    for (int i = 19; i >= 0; i--) {
        if (depth[parent[u][i]] >= depth[v]) {
            u = parent[u][i];
        }
    }
    if (u == v) {
        return u;
    }
    for (int i = 19; i >= 0; i--) {
        if (parent[u][i] != parent[v][i]) {
            u = parent[u][i];
            v = parent[v][i];
        }
    }
    return parent[u][0];
}

int dist(int u, int v) {
    return depth[u] + depth[v] - 2 * depth[lca(u, v)];
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int q;
    cin >> q;

    while (q--) {
        cin >> n;
        for (int i = 1; i <= n; i++) {
            adj[i].clear();
            depth[i] = 0;
            for (int j = 0; j < 20; j++) {
                parent[i][j] = 0;
            }
        }
        for (int i = 1; i < n; i++) {
            int u, v;
            cin >> u >> v;
            adj[u].push_back(v);
            adj[v].push_back(u);
        }

        dfs(1, 0);

        cin >> m;
        vector<int> s(m), t(m);
        for (int i = 0; i < m; i++) {
            cin >> s[i] >> t[i];
        }

        vector<int> used(n + 1, 0);
        bool ok = true;
        for (int i = 0; i < m; i++) {
            if (s[i] == t[i]) continue;
            int d = dist(s[i], t[i]);
            int u = s[i], v = t[i];
            while (d--) {
                if (used[u]) {
                    ok = false;
                    break;
                }
                used[u] = 1;
                u = parent[u][0];
            }
            if (!ok) break;
        }

        cout << (ok ? "Yes" : "No") << '\n';
    }

    return 0;
}

• 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