#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int K = 17;
vector<int> link[100002];
int par[100002], LCADB[100002][K], sz[100002], depth[100002];
int val[100002];
inline int find(int x){
if(x==par[x]) return x;
return find(par[x]);
}
inline void sps_dfs(int x, int p){
for(int i=1; i<K; i++) LCADB[x][i] = LCADB[LCADB[x][i-1]][i-1];
for(int y: link[x]){
if(p != y){
par[y] = LCADB[y][0] = x;
depth[y] = depth[x] + 1;
sps_dfs(y, x);
}
}
}
inline void merge(int x, int y){
int rx = find(x), ry = find(y);
if(rx==ry) return;
if(sz[rx] < sz[ry]) swap(rx, ry), swap(x, y);
link[x].push_back(y), link[y].push_back(x);
LCADB[y][0] = par[y] = x, sz[rx] += sz[ry];
depth[y] = depth[x] + 1;
sps_dfs(y, x);
}
inline int getLCA(int x, int y){
if(depth[x] > depth[y]) swap(x, y);
for(int d=0; d<K; d++) if((depth[y]-depth[x])&(1<<d)) y = LCADB[y][d];
if(x==y) return x;
for(int d=K-1; d>=0; d--) if(LCADB[x][d] != LCADB[y][d]) x = LCADB[x][d], y = LCADB[y][d];
return par[x];
}
int n, m;
void dfs(int x, int p=-1){
for(int y: link[x]){
if(y==p) continue;
dfs(y, x);
val[x] += val[y];
}
}
int main(){
scanf("%d %d", &n, &m);
for(int i=1; i<=n; i++) par[i] = i, sz[i] = 1;
while(m--){
int x, y;
scanf("%d %d", &x, &y);
if(find(x) == find(y)){
val[x]++, val[y]++;
val[getLCA(x, y)] -= 2;
}
else merge(x, y);
}
for(int i=1; i<=n; i++) if(par[i] == i) dfs(i);
for(int i=1; i<=n; i++){
if(par[i] != i && !val[i]) printf("%d %d\n", par[i], i);
}
}
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:57:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
57 | scanf("%d %d", &n, &m);
| ~~~~~^~~~~~~~~~~~~~~~~
pipes.cpp:61:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
61 | scanf("%d %d", &x, &y);
| ~~~~~^~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
6492 KB |
Output is correct |
2 |
Incorrect |
1 ms |
6492 KB |
Wrong number of edges |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
6744 KB |
Output is correct |
2 |
Correct |
6 ms |
6836 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
207 ms |
6748 KB |
Output is correct |
2 |
Correct |
193 ms |
6748 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
500 ms |
7248 KB |
Output is correct |
2 |
Correct |
478 ms |
7036 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
830 ms |
9592 KB |
Output is correct |
2 |
Correct |
714 ms |
8484 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1667 ms |
12656 KB |
Output is correct |
2 |
Correct |
1262 ms |
12880 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2644 ms |
13520 KB |
Output is correct |
2 |
Correct |
2212 ms |
13572 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4329 ms |
14160 KB |
Output is correct |
2 |
Correct |
3253 ms |
14124 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
5040 ms |
13908 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
5042 ms |
13944 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |