#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,popcnt,sse4")
#define pii pair<int,int>
#define fs first
#define sc second
#define ll long long
const int mxn = 5e5+10;
int N,M;
vector<pii> paths[mxn];
int deg[mxn];
bitset<mxn> done;
vector<int> v;
vector<int> cc;
int col[mxn];
void dfs(int now,int c){
cc.push_back(now);
col[now] = c;
for(auto [nxt,___]:paths[now]){
if(!col[nxt])dfs(nxt,-c);
}
return;
}
bool choose(int c){
for(auto &i:cc){
if(col[i] == c)continue;
bool flag = false;
for(auto [nxt,w]:paths[i]){
if(w == 1)flag = true;
}
if(!flag)return false;
}
return true;
}
void calc(int now){
cc.clear();
dfs(now,1);
if(choose(1)){
for(auto &i:cc)if(col[i] == 1)v.push_back(i);
}
else if(choose(-1)){
for(auto &i:cc)if(col[i] == -1)v.push_back(i);
}
else{
cout<<-1;
exit(0);
}
return;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>N>>M;
for(int i = 1;i<=M;i++){
int a,b;
cin>>a>>b;
paths[a].push_back(pii(b,1));
paths[b].push_back(pii(a,-1));
}
for(int i = 1;i<=N;i++){
if(!col[i])calc(i);
}
cout<<v.size()<<'\n';
for(auto &i:v)cout<<i<<' ';cout<<'\n';
return 0;
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:72:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
72 | for(auto &i:v)cout<<i<<' ';cout<<'\n';
| ^~~
Main.cpp:72:29: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
72 | for(auto &i:v)cout<<i<<' ';cout<<'\n';
| ^~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
124 ms |
50632 KB |
Output is correct |
2 |
Correct |
118 ms |
35232 KB |
Output is correct |
3 |
Correct |
3 ms |
15964 KB |
Output is correct |
4 |
Correct |
35 ms |
21204 KB |
Output is correct |
5 |
Correct |
72 ms |
34464 KB |
Output is correct |
6 |
Correct |
118 ms |
42912 KB |
Output is correct |
7 |
Correct |
82 ms |
39352 KB |
Output is correct |
8 |
Correct |
102 ms |
42676 KB |
Output is correct |
9 |
Correct |
242 ms |
40128 KB |
Output is correct |
10 |
Incorrect |
194 ms |
35036 KB |
Output isn't correct |
11 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
120 ms |
50484 KB |
Output is correct |
2 |
Correct |
107 ms |
43512 KB |
Output is correct |
3 |
Correct |
77 ms |
38328 KB |
Output is correct |
4 |
Incorrect |
187 ms |
36044 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
5 ms |
16216 KB |
Output is correct |
2 |
Correct |
6 ms |
16220 KB |
Output is correct |
3 |
Correct |
4 ms |
16068 KB |
Output is correct |
4 |
Incorrect |
6 ms |
16216 KB |
Output isn't correct |
5 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
124 ms |
50632 KB |
Output is correct |
2 |
Correct |
118 ms |
35232 KB |
Output is correct |
3 |
Correct |
3 ms |
15964 KB |
Output is correct |
4 |
Correct |
35 ms |
21204 KB |
Output is correct |
5 |
Correct |
72 ms |
34464 KB |
Output is correct |
6 |
Correct |
118 ms |
42912 KB |
Output is correct |
7 |
Correct |
82 ms |
39352 KB |
Output is correct |
8 |
Correct |
102 ms |
42676 KB |
Output is correct |
9 |
Correct |
242 ms |
40128 KB |
Output is correct |
10 |
Incorrect |
194 ms |
35036 KB |
Output isn't correct |
11 |
Halted |
0 ms |
0 KB |
- |