Submission #1080067

#	Time	Username	Problem	Language	Result	Execution time	Memory
1080067		jk_	Pipes (CEOI15_pipes)	C++14	40 / 100	861 ms	65536 KiB

pipes

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

struct ufind {
  vector<int> c;
  ufind(int n) : c(n) { iota(c.begin(), c.end(), 0); }
  int find(int k) { return c[k] == k ? k : (c[k] = find(c[k])); }
  void unite(int a, int b) { c[find(a)] = find(b); }
};

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

  int n, m; cin >> n >> m;
  vector<vector<pair<int, int>>> g(n);
  array<ufind, 2> msts{{ufind(n), ufind(n)}};

  for (int i = 0; i < m; ++i) {
    int a, b; cin >> a >> b; --a; --b;
    for (auto& mst : msts) {
      if (mst.find(a) != mst.find(b)) {
        mst.unite(a, b);
        g[a].emplace_back(b, i);
        g[b].emplace_back(a, i);
        break;
      }
    }
  }

  vector<pair<int, int>> bridges;
  vector<bool> visited(n);
  vector<int> pre(n, -1), low(n, -1);
  int timer=0;

  auto dfs = [&](auto&& self, int v, int e = -1) -> void {
    visited[v] = true;
    pre[v] = low[v] = timer++;
    for (auto [w, f] : g[v]) {
      if (f == e) continue;
      if (visited[w]) {
        low[v] = min(low[v], pre[w]);
      } else {
        self(self, w, f);
        low[v] = min(low[v], low[w]);
        if (low[w] > pre[v]) {
          cout << v+1 << ' ' << w+1 << '\n';
        }
      }
    }
  };
  for (int i = 0; i < n; ++i)
    if (!visited[i])
      dfs(dfs, i);
}

Compilation message (stderr)

pipes.cpp: In lambda function:
pipes.cpp:39:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   39 |     for (auto [w, f] : g[v]) {
      |               ^

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10