// In the name of the God
#include <bits/stdc++.h>
#define ll long long
// #define int long long
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define pii pair <int, int>
#define smin(x, y) (x) = min((x), (y))
#define smax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(), (x).end()
using namespace std;
const int inf = 1e9+7;
const int mod = 998244353;
const int maxn = 5e2+5;
int n, m, cnt[maxn];
vector <int> adj[maxn], vec;
queue <int> q;
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 a, b; cin >> a >> b;
adj[--b].pb(--a);
cnt[a]++;
}
for (int i = 0; i < n; i++) {
if (!cnt[i]) q.push(i);
}
while (q.size()) {
int v = q.front(); q.pop();
vec.pb(v);
for (int u : adj[v]) {
cnt[u]--;
if (!cnt[u]) q.push(u);
}
}
if (vec.size() != n) cout << -1 << '\n';
else {
cout << n << '\n';
for (int v : vec) cout << v << ' ' << 1 << '\n';
}
return 0;
}
Compilation message
Main.cpp: In function 'int32_t main()':
Main.cpp:42:20: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
42 | if (vec.size() != n) cout << -1 << '\n';
| ~~~~~~~~~~~^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
600 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
600 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
600 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
