#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 1;
int n, m, h[N], mnh[N], edges, u, v, i;
bool vis[N];
vector<pair<int, int>> g[N];
int root1(int& v){
return (h[v] == -1 ? v : h[v] = root1(h[v]));
}
int root2(int& v){
return (mnh[v] == -1 ? v : mnh[v] = root2(mnh[v]));
}
void merge1(int& u, int& v){
int r1 = root1(v);
int r2 = root1(u);
h[r1] = r2;
edges++;
g[v].push_back({u, edges});
g[u].push_back({v, edges});
}
void merge2(int& u, int& v){
int r1 = root2(u);
int r2 = root2(v);
if (r1 == r2)
return;
mnh[r1] = r2;
edges++;
g[v].push_back({u, edges});
g[u].push_back({v, edges});
}
void dfs(int& v, pair<int, int> prev = {-1, -1}){
vis[v] = 1;
if (prev.first == -1)
h[v] = 0;
mnh[v] = h[v];
for (auto& [u, id] : g[v]){
if (prev.first == u and prev.second == id)
continue;
mnh[v] = min(mnh[v], h[u]);
if (vis[u])
continue;
h[u] = h[v] + 1;
dfs(u, {v, id});
mnh[v] = min(mnh[v], mnh[u]);
if (mnh[u] >= h[u])
printf("%d %d\n", u, v);
}
}
int main(){
scanf("%d%d", &n, &m);
for (i=1; i<=n; i++)
h[i] = mnh[i] = -1;
for (i=0; i<m; i++){
scanf("%d%d", &u, &v);
if (root1(u) != root1(v))
merge1(u, v);
else if (root2(u) != root2(v))
merge2(u, v);
}
for (i=1; i<=n; i++)
h[i] = mnh[i] = n + 100;
for (v = 1; v <= n; v++)
if (!vis[v])
dfs(v);
}
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:69:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
69 | scanf("%d%d", &n, &m);
| ~~~~~^~~~~~~~~~~~~~~~
pipes.cpp:75:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
75 | scanf("%d%d", &u, &v);
| ~~~~~^~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2652 KB |
Output is correct |
2 |
Correct |
1 ms |
2652 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
3164 KB |
Output is correct |
2 |
Correct |
4 ms |
2908 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
79 ms |
3036 KB |
Output is correct |
2 |
Correct |
80 ms |
3008 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
134 ms |
3668 KB |
Output is correct |
2 |
Correct |
159 ms |
3424 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
216 ms |
5460 KB |
Output is correct |
2 |
Correct |
196 ms |
4996 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
284 ms |
10872 KB |
Output is correct |
2 |
Runtime error |
261 ms |
17748 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
457 ms |
12112 KB |
Output is correct |
2 |
Runtime error |
484 ms |
25824 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
609 ms |
14604 KB |
Output is correct |
2 |
Runtime error |
563 ms |
31572 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
727 ms |
14420 KB |
Output is correct |
2 |
Runtime error |
701 ms |
37132 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
881 ms |
13804 KB |
Output is correct |
2 |
Runtime error |
907 ms |
44500 KB |
Memory limit exceeded |
3 |
Halted |
0 ms |
0 KB |
- |