Submission #755502

#	Time	Username	Problem	Language	Result	Execution time	Memory
755502		The_Samurai	Pipes (BOI13_pipes)	C++17	74.07 / 100	198 ms	19272 KiB

pipes

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>

using namespace std;

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

    int n, m;
    cin >> n >> m;

    vector<vector<pair<int, int>>> g(n + 1);
    vector<int> cnt(n + 1), ans(m), a(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        g[u].emplace_back(v, i);
        g[v].emplace_back(u, i);
    }
    if (n < m + 1) {
        cout << 0;
        return 0;
    }
    queue<int> q;
    vector<bool> vis(n + 1);
    for (int i = 1; i <= n; i++) {
        cnt[i] = g[i].size();
        if (cnt[i] == 1) {
            q.push(i);
        }
    }
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        vis[u] = true;
        for (auto [v, i]: g[u]) {
            if (vis[v]) continue;
            cnt[v]--;
            if (cnt[v] == 1) q.push(v);
            ans[i] = a[u] * 2;
            a[v] -= a[u];
        }
    }
    for (int x: ans) cout << x << '\n';

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 44.074074074074076 / 70