Gym - 101915D Largest Group 最大团

//Hungary
#include<bits/stdc++.h>
using namespace std;
#define N 50
int useif[N];   //记录y中节点是否使用 0表示没有访问过，1为访问过
int link[N];   //记录当前与y节点相连的x的节点
int mat[N][N]; //记录连接x和y的边，如果i和j之间有边则为1，否则为0
int gn, gm;   //二分图中x和y中点的数目
int can(int t) {
        int i;
        for (i = 1; i <= gm; i++) {
                if (useif[i] == 0 && mat[t][i]) {
                        useif[i] = 1;
                        if (link[i] == -1 || can(link[i])) {
                                link[i] = t;
                                return 1;
                        }
                }
        }
        return 0;
}
int MaxMatch() {
        int i, num;
        num = 0;
        memset(link, 0xff, sizeof(link));
        for (i = 1; i <= gn; i++) {
                memset(useif, 0, sizeof(useif));
                if (can(i)) {
                        num++;
                }
        }
        return num;
}
int main() {
        int TCASE;
        scanf("%d", &TCASE);
        while (TCASE--) {
                int n, k;
                int u, v;
                scanf("%d %d", &n, &k);
                gn = gm = n;
                memset(mat, 0, sizeof(mat));
                for (int i = 1; i <= k; i++) {
                        scanf("%d %d", &u, &v);
                        mat[u][v] = 1;
                }
                for (int i = 1; i <= n; i++) {
                        for (int j = 1; j <= n; j++) {
                                mat[i][j] = mat[i][j] ^ 1;
                        }
                }
                int ans = n * 2;
                ans -= MaxMatch();
                printf("%d\n", ans);
        }
}