Submission #36020

#	Time	Username	Problem	Language	Result	Execution time	Memory
36020		funcsr	Pipes (CEOI15_pipes)	C++14	0 / 100	1182 ms	8340 KiB

pipes

#include <iostream>
#include <fstream>
#include <bitset>
#include <cassert>
#include <vector>
#define rep(i, n) for (int i=0; i<(n); i++)
#define INF 1145141919
#define pb push_back
#define _1 first
#define _2 second

using namespace std;
typedef pair<int, int> P;

struct UnionFind {
  int U[100000];
  UnionFind(int N) {
    rep(i, N) U[i] = i;
  }
  int find(int x) {
    if (U[x] == x) return x;
    return U[x] = find(U[x]);
  }
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if (x == y) return;
    U[x] = y;
  }
  bool same(int x, int y) {
    return find(x) == find(y);
  }
};

int N, M;
vector<int> G[100000];

int R[100000];
void dfs(int x, int p, int r) {
  R[x] = r;
  for (int t : G[x]) {
    if (t == p) continue;
    dfs(t, x, r+1);
  }
}

int T[100000];
void dfs2(int x, int p) {
  for (int t : G[x]) {
    if (t == p) continue;
    dfs2(t, x);
    T[x] += T[t];
  }
  if (p != -1 && T[x] == 0) cout << x+1 << " " << p+1 << "\n";
}


signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  cin >> N >> M;
  UnionFind uf1(N), uf2(N);
  vector<P> backwards;
  rep(_, M) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    if (!uf1.same(u, v)) {
      G[u].pb(v), G[v].pb(u);
      uf1.unite(u, v);
    }
    else if (!uf2.same(u, v)) {
      backwards.pb(P(u, v));
      uf2.unite(u, v);
    }
  }
  rep(i, N) if (uf1.find(i) == i) dfs(i, -1, 0);
  for (P p : backwards) {
    int u = p._1, v = p._2;
    if (R[u] > R[v]) swap(u, v);
    //cout<<"u="<<u<<","<<v<<"\n";
    T[v]++, T[u]--;
  }
  rep(i, N) if (uf1.find(i) == i) dfs2(i, -1);
  return 0;
}

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