[백준 5567번] 결혼식

소스코드

---

#include <iostream>
using namespace std;
int n, m, f[501], map[501][501], a, b,cnt=0;
int main() {
    cin >> n >> m;
    while (m--) {
        cin >> a >> b;
        map[a][b] = 1, map[b][a]=1;
        if (a == 1) { f[b] = 1; }
        else if (b == 1) { f[a] = 1; }
    }
    for (int i = 2; i <= n; i++) {
        if (map[1][i]==1) {
            for (int j = 2; j <= n; j++) {
                if (map[i][j]==1) {
                    f[j] = 1;
                }
            }
        }
    }
    for (int i = 2; i <= n; i++) {
        if (f[i]==1) { cnt++; }
    }
    cout << cnt << '\n';
    return 0;
}