mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-21 18:31:59 +00:00
41 lines
908 B
C++
41 lines
908 B
C++
|
#include <bits/stdc++.h>
|
||
|
|
||
|
using namespace std;
|
||
|
|
||
|
int n, m, a, b, f[105][105], ans[105];
|
||
|
|
||
|
int main() {
|
||
|
cin >> n >> m;
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
for (int j = 1; j <= n; j++) {
|
||
|
f[i][j] = i == j ? 0 : 0x3f3f3f3f;
|
||
|
}
|
||
|
}
|
||
|
for (int i = 1; i <= m; i++) {
|
||
|
cin >> a >> b;
|
||
|
f[a][b] = 1;
|
||
|
}
|
||
|
for (int k = 1; k <= n; k++) {
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
for (int j = 1; j <= n; j++) {
|
||
|
f[i][j] = min(f[i][j], f[i][k] + f[k][j]);
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
for (int j = 1; j <= n; j++) {
|
||
|
if (f[i][j] != 0x3f3f3f3f && f[i][j] > 0) {
|
||
|
ans[i]++;
|
||
|
ans[j]++;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
if (ans[i] == n - 1) {
|
||
|
ans[0]++;
|
||
|
}
|
||
|
}
|
||
|
cout << ans[0] << endl;
|
||
|
return 0;
|
||
|
}
|