#include <utility>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <set>
using namespace std;
typedef pair<int,int> ii;
int n,m;
int d[100005], pa[100005], sz[100005];
vector<int> G[100005];
set<ii> bad;
struct ufds{
int p[100005];
ufds(){
for (int i = 0; i <= 100000; i++) p[i] = i;
}
inline int find(int x){
return p[x] == x ? x : p[x] = find(p[x]);
}
inline void un(int x, int y){
p[x] = y;
}
} u1 = ufds(), u2 = ufds();
void dfs(int u, int p){
///join at side bad
u2.p[u] = u;
pa[u] = p;
for (auto v : G[u]){
if (v == p) continue;
else{
d[v] = d[u]+1;
dfs(v,u);
}
}
}
int main(){
scanf("%d%d",&n,&m);
for (int i = 1; i <= n; i++) sz[i] = 1; ///serious error
for (int i = 0; i < m; i++){
int u,v;
scanf("%d%d",&u,&v);
int pu = u1.find(u), pv = u1.find(v);
//printf("%d -> %d, %d -> %d\n",u,pu,v,pv);
if (pu == pv){
//printf("update path %d %d\n",u,v);
///make all edges along this path bad
///all edges along path are only changed once, amortised O()
u = u2.find(u), v = u2.find(v);
while (u != v){
if (d[u] < d[v]) swap(u,v);
bad.insert({min(u,pa[u]),max(u,pa[u])});
//printf("bad %d %d\n",u,pa[u]);
u2.un(u,pa[u]);
u = pa[u];
u = u2.find(u);
}
}
else{
//printf("join %d %d\n",u,v);
///join the two components
if (sz[pu] < sz[pv]){
swap(pu,pv);
swap(u,v);
}
///join small v to big u
u1.un(pv,pu);
sz[pu] += sz[pv];
///add edge
G[u].push_back(v);
G[v].push_back(u);
///restart dfs
d[v] = d[u]+1;
dfs(v,u);
}
}
for (int u = 1; u <= n ;u++){
for (auto v : G[u]){
if (v > u && bad.find({u,v}) == bad.end()){
printf("%d %d\n",u,v);
}
}
}
}
Compilation message
pipes.cpp: In function 'int main()':
pipes.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d",&n,&m);
~~~~~^~~~~~~~~~~~~~
pipes.cpp:42:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d",&u,&v);
~~~~~^~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
3456 KB |
Output is correct |
2 |
Correct |
6 ms |
3456 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
13 ms |
3968 KB |
Output is correct |
2 |
Correct |
13 ms |
4096 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
149 ms |
4832 KB |
Output is correct |
2 |
Correct |
147 ms |
4892 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
249 ms |
6008 KB |
Output is correct |
2 |
Correct |
315 ms |
6012 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
424 ms |
7032 KB |
Output is correct |
2 |
Correct |
373 ms |
7544 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
606 ms |
10488 KB |
Output is correct |
2 |
Runtime error |
568 ms |
27896 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
908 ms |
12280 KB |
Output is correct |
2 |
Runtime error |
892 ms |
19576 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1335 ms |
13820 KB |
Output is correct |
2 |
Runtime error |
1253 ms |
24696 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1490 ms |
13212 KB |
Output is correct |
2 |
Runtime error |
1513 ms |
28768 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1722 ms |
13048 KB |
Output is correct |
2 |
Runtime error |
1723 ms |
40424 KB |
Memory limit exceeded (if you are sure your verdict is not MLE, please contact us) |