xmu 1100无向图最小割

#include <iostream>
using namespace std;
int mat[110][110];
int res;

void Mincut(int n) {
	int node[110], dist[110];
	bool visit[110];
	int i, prev, maxj, j, k;
	for (i = 0; i < n; i++)
		node[i] = i;
	while (n > 1) {
		int maxj = 1;
		for (i = 1; i < n; i++) { //初始化到已圈集合的割大小
			dist[node[i]] = mat[node[0]][node[i]];
			if (dist[node[i]] > dist[node[maxj]])
				maxj = i;
		}
		prev = 0;
		memset(visit, false, sizeof (visit));
		visit[node[0]] = true;
		for (i = 1; i < n; i++) {
			if (i == n - 1) { //只剩最后一个没加入集合的点，更新最小割
				res = min(res, dist[node[maxj]]);
				for (k = 0; k < n; k++) //合并最后一个点以及推出它的集合中的点
					mat[node[k]][node[prev]] = (mat[node[prev]][node[k]] += mat[node[k]][node[maxj]]);
				node[maxj] = node[--n]; //缩点后的图
			}
			visit[node[maxj]] = true;
			prev = maxj;
			maxj = -1;
			for (j = 1; j < n; j++)
				if (!visit[node[j]]) { //将上次求的maxj加入集合，合并与它相邻的边到割集
					dist[node[j]] += mat[node[prev]][node[j]];
					if (maxj == -1 || dist[node[maxj]] < dist[node[j]])
						maxj = j;
				}
		}

	}
	return;
}

int main() {
	int n, m, a, b;
	while (scanf("%d%d", &n, &m) != EOF) {
		res = (1 << 29);
		memset(mat, 0, sizeof (mat));
		while (m--) {
			scanf("%d%d", &a, &b);
			mat[a][b] += 1;
			mat[b][a] += 1;
		}
		Mincut(n);
		printf("%d\n", res);
	}
}