제출 #1132965

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1132965		Kubeti	Pipes (CEOI15_pipes)	C++20	10 / 100	590 ms	28220 KiB

pipes

#include <bits/stdc++.h>
#define int long long

using namespace std;

const int nmax = 2e5 + 1, mod = 1e6 + 7;

struct DSU {
  int root[nmax], sz[nmax];

  void init(int n) {
    for(int i = 1; i <= n; i++) {
      root[i] = i;
      sz[i] = 1;
    }
  }

  int find(int a) {
    if(root[a] == a) {
      return a;
    }
    return root[a] = find(root[a]);
  }

  void unite(int a, int b) {
    assert(a != b);
    if(sz[a] > sz[b]) {
      swap(a, b);
    }
    root[a] = b;
    sz[b] += sz[a];
  }
} d1, d2;

vector<int> adj[nmax], tj[nmax];
stack<int> st;
int low[nmax];
int t[nmax];
bool f[nmax];
int ind, comp;

void dfs(int i, int anc = 0) {
  // cout << "!" << i << " " << anc << '\n';
  f[i] = 1;
  st.push(i);
  t[i] = low[i] = t[anc] + 1;
  for(auto it : adj[i]) {
    //cout << "!" << i << " " << it << '\n';
    if(f[it] && it != anc) {
      low[i] = min(low[i], t[it]);
    } else if(!f[it]) {
      dfs(it, i);
      low[i] = min(low[i], low[it]);
      if(t[i] <= low[it]) {
        comp++;
        while(st.top() != it) {
          tj[comp].push_back(st.top());
          st.pop();
        }
        st.pop();
        tj[comp].push_back(it);
        tj[comp].push_back(i);
      }
    }
  }
}

int32_t main(){
  ios_base::sync_with_stdio(0);cin.tie(0);
  int n, m;
  cin >> n >> m;
  d1.init(n), d2.init(n);
  for(int i = 1; i <= m; i++) {
    int a, b;
    cin >> a >> b;
    if(d1.find(a) != d1.find(b)) {
      d1.unite(d1.find(a), d1.find(b));
      adj[a].push_back(b);
      adj[b].push_back(a);
      // cout << "!" << a << " " << b << '\n';
    } else if(d2.find(a) != d2.find(b)) {
      d2.unite(d2.find(a), d2.find(b));
      // cout << "!" << a << " " << b << '\n';
      adj[a].push_back(b);
      adj[b].push_back(a);
    }
  }
  for(int i = 1; i <= n; i++) {
    if(!f[i]) {
      while(!st.empty()) {
        st.pop();
      }
      dfs(i);
    }
  }
  for(int i = 1; i <= comp; i++) {
    if(tj[i].size() == 2) {
      cout << tj[i][0] << " " << tj[i][1] << '\n';
    }
  }
  return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 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