#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
#define lg long long
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
const lg N = 2e5+5;
vector<lg> adj[N];
lg in[N], state[N];
int main()
{
fastio;
lg n, m;
cin >> n >> m;
for(int i = 0; i < m; i++)
{
lg u, v;
cin >> u >> v;
adj[u].push_back(v);
in[v]++;
}
queue<lg> q;
lg z = 0;
for(int i = 1; i <= n; i++)
{
if(in[i]) continue;
z++;
q.push(i);
}
vector<lg> a;
while(q.size())
{
lg u = q.front();
q.pop();
lg x = 0;
for(auto it : adj[u])
{
if(!x) a.push_back(u*2+1);
x++;
in[it]--;
if(!in[it])
{
q.push(it);
z++;
}
}
if(adj[u].empty())
{
a.push_back(u*2);
}
}
if(z < n)
{
cout << "-1\n";
return 0;
}
cout << n << '\n';
reverse(a.begin(), a.end());
for(auto it : a) cout << it/2 << ' ' << it%2 << '\n';
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
8024 KB |
Output is correct |
| 2 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 3 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 4 |
Correct |
2 ms |
8088 KB |
Output is correct |
| 5 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 6 |
Correct |
2 ms |
8024 KB |
Output is correct |
| 7 |
Correct |
2 ms |
8276 KB |
Output is correct |
| 8 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 9 |
Correct |
2 ms |
8108 KB |
Output is correct |
| 10 |
Correct |
2 ms |
8104 KB |
Output is correct |
| 11 |
Correct |
3 ms |
8024 KB |
Output is correct |
| 12 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 13 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 14 |
Correct |
2 ms |
8028 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
91 ms |
16332 KB |
Output is correct |
| 2 |
Correct |
72 ms |
16484 KB |
Output is correct |
| 3 |
Correct |
33 ms |
12492 KB |
Output is correct |
| 4 |
Correct |
70 ms |
16328 KB |
Output is correct |
| 5 |
Correct |
75 ms |
16272 KB |
Output is correct |
| 6 |
Correct |
67 ms |
16328 KB |
Output is correct |
| 7 |
Correct |
69 ms |
16388 KB |
Output is correct |
| 8 |
Correct |
53 ms |
14588 KB |
Output is correct |
| 9 |
Correct |
67 ms |
16332 KB |
Output is correct |
| 10 |
Correct |
68 ms |
16352 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
8024 KB |
Output is correct |
| 2 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 3 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 4 |
Correct |
2 ms |
8088 KB |
Output is correct |
| 5 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 6 |
Correct |
2 ms |
8024 KB |
Output is correct |
| 7 |
Correct |
2 ms |
8276 KB |
Output is correct |
| 8 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 9 |
Correct |
2 ms |
8108 KB |
Output is correct |
| 10 |
Correct |
2 ms |
8104 KB |
Output is correct |
| 11 |
Correct |
3 ms |
8024 KB |
Output is correct |
| 12 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 13 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 14 |
Correct |
2 ms |
8028 KB |
Output is correct |
| 15 |
Correct |
91 ms |
16332 KB |
Output is correct |
| 16 |
Correct |
72 ms |
16484 KB |
Output is correct |
| 17 |
Correct |
33 ms |
12492 KB |
Output is correct |
| 18 |
Correct |
70 ms |
16328 KB |
Output is correct |
| 19 |
Correct |
75 ms |
16272 KB |
Output is correct |
| 20 |
Correct |
67 ms |
16328 KB |
Output is correct |
| 21 |
Correct |
69 ms |
16388 KB |
Output is correct |
| 22 |
Correct |
53 ms |
14588 KB |
Output is correct |
| 23 |
Correct |
67 ms |
16332 KB |
Output is correct |
| 24 |
Correct |
68 ms |
16352 KB |
Output is correct |
| 25 |
Correct |
101 ms |
19668 KB |
Output is correct |
| 26 |
Correct |
64 ms |
18892 KB |
Output is correct |
| 27 |
Correct |
77 ms |
20188 KB |
Output is correct |
| 28 |
Correct |
97 ms |
22608 KB |
Output is correct |
| 29 |
Correct |
78 ms |
18740 KB |
Output is correct |
| 30 |
Correct |
96 ms |
22392 KB |
Output is correct |
| 31 |
Correct |
16 ms |
10072 KB |
Output is correct |
| 32 |
Correct |
110 ms |
18432 KB |
Output is correct |
| 33 |
Correct |
122 ms |
24320 KB |
Output is correct |
| 34 |
Correct |
90 ms |
18884 KB |
Output is correct |
| 35 |
Correct |
145 ms |
24512 KB |
Output is correct |
| 36 |
Correct |
73 ms |
18184 KB |
Output is correct |
| 37 |
Correct |
114 ms |
23052 KB |
Output is correct |
| 38 |
Correct |
99 ms |
21364 KB |
Output is correct |
| 39 |
Correct |
123 ms |
24256 KB |
Output is correct |
| 40 |
Correct |
134 ms |
22536 KB |
Output is correct |
| 41 |
Correct |
109 ms |
22208 KB |
Output is correct |
| 42 |
Correct |
137 ms |
25024 KB |
Output is correct |
| 43 |
Correct |
84 ms |
19592 KB |
Output is correct |
| 44 |
Correct |
190 ms |
25432 KB |
Output is correct |
| 45 |
Correct |
94 ms |
18968 KB |
Output is correct |
| 46 |
Correct |
106 ms |
22544 KB |
Output is correct |
