Submission #995712

#	Time	Username	Problem	Language	Result	Execution time	Memory
995712		MilosMilutinovic	Pipes (BOI13_pipes)	C++14	74.07 / 100	130 ms	23636 KiB

pipes

#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<long long> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<vector<array<int, 2>>> g(n);
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back({y, i});
    g[y].push_back({x, i});
  }
  if (m >= n) {
    cout << 0 << '\n';
    return 0;
  }
  if (n == 1) {
    cout << 2 * a[0] << '\n';
    return 0;
  }
  if (m < n) {
    vector<long long> res(m);
    function<void(int, int)> Dfs = [&](int v, int pv) {
      for (auto& e : g[v]) {
        int u = e[0];
        if (u == pv) {
          continue;
        }
        Dfs(u, v);
        if (a[u] != 0) {
          res[e[1]] = 2 * a[u];
          a[v] -= a[u];
        }
      }
    };
    Dfs(0, 0);
    if (a[0] != 0) {
      cout << 0 << '\n';
      return 0;
    }
    for (int i = 0; i < m; i++) {
      cout << res[i] << '\n';
    }
    return 0;
  }
  return 0;
}

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