// In the name of God
// Hope is last to die
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define pb push_back
// #define int long long
#define S second
#define F first
#define mp make_pair
#define smax(x, y) (x) = max((x), (y))
#define smin(x, y) (x) = min((x), (y))
#define all(x) (x).begin(), (x).end()
#define len(x) ((int)(x).size())
const int maxn = 2e5 + 5;
const int inf = 1e9 + 7;
int n, m, mark[maxn];
vector<int> adj[maxn], topol;
void dfs(int v){
mark[v] = 1;
for(auto u: adj[v]){
if(!mark[u]) dfs(u);
else if(mark[u] == 1){
cout << -1 << '\n';
exit(0);
}
}
topol.pb(v);
mark[v] = 2;
}
void topolo(){
for(int i = 1; i <= n; i++) if(!mark[i]) dfs(i);
reverse(all(topol));
}
int32_t main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
for(int i = 0; i < m; i++){
int u, v; cin >> u >> v;
adj[v].pb(u);
}
topolo();
cout << n << '\n';
for(int i = 0; i < n; i++){
cout << topol[i] << ' ' << 1 << '\n';
}
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4952 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
1 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
2 ms |
5156 KB |
Output is correct |
8 |
Correct |
2 ms |
4956 KB |
Output is correct |
9 |
Correct |
2 ms |
4956 KB |
Output is correct |
10 |
Correct |
2 ms |
4956 KB |
Output is correct |
11 |
Correct |
1 ms |
4956 KB |
Output is correct |
12 |
Correct |
2 ms |
4956 KB |
Output is correct |
13 |
Correct |
1 ms |
4956 KB |
Output is correct |
14 |
Correct |
1 ms |
4968 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
69 ms |
15072 KB |
Output is correct |
2 |
Correct |
71 ms |
15048 KB |
Output is correct |
3 |
Correct |
32 ms |
10192 KB |
Output is correct |
4 |
Correct |
66 ms |
15056 KB |
Output is correct |
5 |
Correct |
73 ms |
15156 KB |
Output is correct |
6 |
Correct |
65 ms |
15240 KB |
Output is correct |
7 |
Correct |
68 ms |
15040 KB |
Output is correct |
8 |
Correct |
50 ms |
13000 KB |
Output is correct |
9 |
Correct |
72 ms |
15300 KB |
Output is correct |
10 |
Correct |
83 ms |
15096 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4952 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
1 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
2 ms |
5156 KB |
Output is correct |
8 |
Correct |
2 ms |
4956 KB |
Output is correct |
9 |
Correct |
2 ms |
4956 KB |
Output is correct |
10 |
Correct |
2 ms |
4956 KB |
Output is correct |
11 |
Correct |
1 ms |
4956 KB |
Output is correct |
12 |
Correct |
2 ms |
4956 KB |
Output is correct |
13 |
Correct |
1 ms |
4956 KB |
Output is correct |
14 |
Correct |
1 ms |
4968 KB |
Output is correct |
15 |
Correct |
69 ms |
15072 KB |
Output is correct |
16 |
Correct |
71 ms |
15048 KB |
Output is correct |
17 |
Correct |
32 ms |
10192 KB |
Output is correct |
18 |
Correct |
66 ms |
15056 KB |
Output is correct |
19 |
Correct |
73 ms |
15156 KB |
Output is correct |
20 |
Correct |
65 ms |
15240 KB |
Output is correct |
21 |
Correct |
68 ms |
15040 KB |
Output is correct |
22 |
Correct |
50 ms |
13000 KB |
Output is correct |
23 |
Correct |
72 ms |
15300 KB |
Output is correct |
24 |
Correct |
83 ms |
15096 KB |
Output is correct |
25 |
Correct |
72 ms |
14932 KB |
Output is correct |
26 |
Correct |
68 ms |
15080 KB |
Output is correct |
27 |
Correct |
88 ms |
15700 KB |
Output is correct |
28 |
Correct |
96 ms |
17748 KB |
Output is correct |
29 |
Correct |
56 ms |
13392 KB |
Output is correct |
30 |
Correct |
99 ms |
17644 KB |
Output is correct |
31 |
Correct |
14 ms |
6868 KB |
Output is correct |
32 |
Correct |
70 ms |
17608 KB |
Output is correct |
33 |
Correct |
147 ms |
20580 KB |
Output is correct |
34 |
Correct |
82 ms |
17864 KB |
Output is correct |
35 |
Correct |
115 ms |
20684 KB |
Output is correct |
36 |
Correct |
77 ms |
17348 KB |
Output is correct |
37 |
Correct |
129 ms |
19916 KB |
Output is correct |
38 |
Correct |
102 ms |
18892 KB |
Output is correct |
39 |
Correct |
124 ms |
20396 KB |
Output is correct |
40 |
Correct |
133 ms |
19568 KB |
Output is correct |
41 |
Correct |
101 ms |
19512 KB |
Output is correct |
42 |
Correct |
152 ms |
20956 KB |
Output is correct |
43 |
Correct |
82 ms |
18116 KB |
Output is correct |
44 |
Correct |
162 ms |
21252 KB |
Output is correct |
45 |
Correct |
77 ms |
17652 KB |
Output is correct |
46 |
Correct |
114 ms |
19420 KB |
Output is correct |