oj.uz

Submission #36026

# Submission time Handle Problem Language Result Execution time Memory
36026 2017-12-04T09:18:01 Z funcsr Pipes (CEOI15_pipes) C++14
100 / 100
 1448 ms 14180 KB 
#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<P> G[100000];

bool used[100000];
int R[100000], T[100000];
void dfs(int x, int pe, int r) {
  used[x] = true;
  R[x] = r;
  for (P pp : G[x]) {
    int t = pp._1;
    if (pp._2 == pe) continue;
    if (used[t]) {
      if (R[x] > R[t]) T[x]++, T[t]--;
      continue;
    }
    dfs(t, pp._2, r+1);
  }
}

void dfs2(int x, int p) {
  used[x] = true;
  for (P pp : G[x]) {
    int t = pp._1;
    if (t == p || used[t]) continue;
    dfs2(t, x);
    T[x] += T[t];
  }
  if (p != -1 && T[x] == 0) printf("%d %d\n", x+1, p+1);
}


signed main() {
  scanf("%d %d", &N, &M);
  UnionFind uf1(N), uf2(N);
  rep(i, M) {
    int u, v;
    scanf("%d %d", &u, &v);
    u--, v--;
    if (!uf1.same(u, v)) {
      G[u].pb(P(v, i)), G[v].pb(P(u, i));
      uf1.unite(u, v);
    }
    else if (!uf2.same(u, v)) {
      G[u].pb(P(v, i)), G[v].pb(P(u, i));
      uf2.unite(u, v);
    }
  }
  rep(i, N) used[i] = false;
  rep(i, N) if (!used[i]) dfs(i, -1, 0);
  rep(i, N) used[i] = false;
  rep(i, N) if (!used[i]) dfs2(i, -1);
  return 0;
}

Compilation message

pipes.cpp: In function 'int main()':
pipes.cpp:66:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &N, &M);
   ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:70:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &u, &v);
     ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 2688 KB Output is correct
2 Correct 4 ms 2688 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 3200 KB Output is correct
2 Correct 8 ms 3072 KB Output is correct

Subtask #3
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 113 ms 3108 KB Output is correct
2 Correct 110 ms 2956 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 204 ms 3752 KB Output is correct
2 Correct 228 ms 3500 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 327 ms 5376 KB Output is correct
2 Correct 282 ms 5052 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 527 ms 10704 KB Output is correct
2 Correct 440 ms 8368 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 772 ms 12016 KB Output is correct
2 Correct 722 ms 9208 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 998 ms 14100 KB Output is correct
2 Correct 962 ms 10904 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1230 ms 14180 KB Output is correct
2 Correct 1171 ms 10904 KB Output is correct

Subtask #10
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1448 ms 13600 KB Output is correct
2 Correct 1364 ms 10748 KB Output is correct