Submission #554572

#	Time	Username	Problem	Language	Result	Execution time	Memory
554572		proma	Jail (JOI22_jail)	C++17	0 / 100	1152 ms	1048584 KiB

jail

#include <bits/stdc++.h>

using namespace std;

const int N = 120005;

int n, m, p[N], s[N], t[N], used[N];
vector <int> g[N], path[N], prisoner[N];

void dfs(int v) {
    for (auto i: g[v]) {
        if (i != p[v]) {
            p[i] = v;
            dfs(i);
        }
    }
}

bool find_cycle(int v) {
    used[v] = 1;
    for (auto i: prisoner[v]) {
        if (used[i] == 1) return true;
        if (!used[i] and find_cycle(i)) return true;
    }
    used[v] = 2;
    return false;
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n; i ++) {
        g[i].clear();
        path[i].clear();
        prisoner[i].clear();
    }
    for (int i = 1; i < n; i ++) {
        int a, b;
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    cin >> m;
    for (int i = 0; i < m; i ++) {
        cin >> s[i] >> t[i];
        p[s[i]] = 0;
        dfs(s[i]);
        for (int j = t[i]; j; j = p[j]) {
            path[i].push_back(j);
        }
        for (int j = 0; j < i; j ++) {
            int f1 = 1, f2 = 1;
            for (auto k: path[i]) {
                if (k == s[j]) f1 = 0;
                if (k == t[j]) f2 = 0;
            }
            for (auto k: path[j]) {
                if (k == t[i]) f1 = 0;
                if (k == s[i]) f2 = 0;
            }
            if (!f1 and !f2) {
                cout << "No\n";
                return;
            }
            if (f1 and !f2) {
                prisoner[i].push_back(j);
            }
            if (!f1 and f2) {
                prisoner[j].push_back(i);
            }
        }
    }
    memset(used, 0, sizeof(used)); /*
    for (int i = 0; i < m; i ++) {
        cout << i << ":";
        for (auto j: prisoner[i]) {
            cout << " " << j;
        }
        cout << endl;
    }*/
    for (int i = 0; i < m; i ++) {
        if (!used[i] and find_cycle(i)) {
            cout << "No\n";
            return;
        }
    }
    cout << "Yes\n";
}

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

    int q;
    cin >> q;
    while (q --) {
        solve();
    }

    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