Submission #585581

#	Time	Username	Problem	Language	Result	Execution time	Memory
585581		1zaid1	Pipes (CEOI15_pipes)	C++17	0 / 100	1814 ms	65536 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
const int M = 1e5+1;
vector<int> node[M];
int a[M], d[M], tt = 1;
bitset<100005> vis;
vector<pair<int, int>> ans;

void dfs(int s) {
    a[s] = tt++;
    vis[s] = true;
    for (int i:node[s]) if (!vis[i]) dfs(i);
    d[s] = tt++;
}

void dfs2(int s, int p = 1) {
    vis[s] = true;
    for (int i:node[s]) {
        if (!vis[i]) dfs2(i, s);
        if (i != p) a[s] = min(a[s], a[i]);
        if (i != p) d[s] = max(d[s], d[i]);
    }
}

void dfs3(int s) {
    vis[s] = true;
    for (int i:node[s]) {
        if (!vis[i]) {
            if (d[i] < d[s] && a[i] > a[s]) ans.push_back({s, i});
            dfs3(i);
        }
    }
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    
    int n, m;
    cin >> n >> m;

    for (int i = 1; i <= m; i++) {
        int a, b;
        cin >> a >> b;

        node[a].push_back(b);
        node[b].push_back(a);
    }

    for (int i = 1; i <= n; i++) if (!vis[i]) dfs(i); vis = 0;
    for (int i = 1; i <= n; i++) if (!vis[i]) dfs2(i); vis = 0;
    for (int i = 1; i <= n; i++) if (!vis[i]) dfs3(i); vis = 0;
    for (auto [a, b]:ans) cout << a << ' ' << b << endl;

    return 0;
}
/*
10 11
1 7
1 8
1 6
2 8
6 7
5 8
2 5
2 3
2 4
3 4
10 9

*/

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:50:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   50 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs(i); vis = 0;
      |     ^~~
pipes.cpp:50:55: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   50 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs(i); vis = 0;
      |                                                       ^~~
pipes.cpp:51:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   51 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs2(i); vis = 0;
      |     ^~~
pipes.cpp:51:56: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   51 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs2(i); vis = 0;
      |                                                        ^~~
pipes.cpp:52:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   52 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs3(i); vis = 0;
      |     ^~~
pipes.cpp:52:56: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   52 |     for (int i = 1; i <= n; i++) if (!vis[i]) dfs3(i); vis = 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