Submission #1080165

#	Time	Username	Problem	Language	Result	Execution time	Memory
1080165		jk_	Pipes (CEOI15_pipes)	C++17	50 / 100	774 ms	51336 KiB

pipes

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

const int N = 100000;

struct ufind {
  array<int, N>& c;
  ufind(array<int, N>& c) : c(c) { 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); }
};

struct edge { int to; int next; };
array<edge, 4*N> edges;
int edges_i = 0;
array<int, N> g;

int timer=0;
array<int, N> pre;
array<int, N> low;

void dfs(int v, int p = -1) {
  pre[v] = low[v] = timer++;
  bool used_p = false;
  for (int e = g[v]; e != -1; e = edges[e].next) {
    int w = edges[e].to;
    if (w == p && !used_p) { used_p = true; continue; }
    if (pre[w] != -1) {
      low[v] = min(low[v], pre[w]);
    } else {
      dfs(w, v);
      low[v] = min(low[v], low[w]);
      if (low[w] > pre[v]) {
        cout << v+1 << ' ' << w+1 << '\n';
      }
    }
  }
};


int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  fill(g.begin(), g.end(), -1);

  int n, m; cin >> n >> m;
  assert(n <= N);
  {
    array<ufind, 2> msts{{ufind(pre), ufind(low)}};

    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);

          edges[edges_i] = {b, g[a]};
          g[a] = edges_i++;

          edges[edges_i] = {a, g[b]};
          g[b] = edges_i++;

          break;
        }
      }
    }
  }

  fill(pre.begin(), pre.end(), -1);
  fill(low.begin(), low.end(), -1);

  for (int i = 0; i < n; ++i)
    if (pre[i] == -1)
      dfs(i);
}

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