Submission #994187

#	Time	Username	Problem	Language	Result	Execution time	Memory
994187		vjudge1	Jail (JOI22_jail)	C++17	0 / 100	666 ms	1048576 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], hv[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, stack<int> &top) {
    col[u] = 1;
    for (int v : g2[u]) {
        if (col[v] == 0) dfs2(v, top);
        else if (col[v] == 1) ok = false;
    }
    col[u] = 2;
    top.push(u);
}

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);
    fill(hv, hv+MAXN, 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;
        hv[edges[i].first] = 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);
        }
    }

    function<void(int)> mv = [&](int idx) {
        int v = nxt(edges[idx].first, edges[idx].second);
        if (hv[v]) {
            if (edges[hv[v]].first == edges[hv[v]].second) {
                ok = false;
                return;
            } else {
                mv(hv[v]);
            }
        }
        hv[edges[idx].first] = 0;
        hv[v] = idx;
        edges[idx].first = v;
    };

    stack<int> top;
    for (int i = 1; i <= m; i++) {
        if (col[i] == 0) dfs2(i, top);
    }
    while (!top.empty() && ok) {
        int i = top.top(); top.pop();
        while (edges[i].first != edges[i].second && ok) {
            mv(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:73:5: warning: control reaches end of non-void function [-Wreturn-type]
   73 |     };
      |     ^

• 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