学习粗:https://blog.csdn.net/ddelphine/article/details/77935670
模板题:http://poj.org/problem?id=2914
#include <iostream>
#include<cstring>
using namespace std;
const int maxn=;
int mat[maxn][maxn];
int res;
inline int min(int a,int b){if(a<b)return a; return b;}
void Mincut(int n) {
int node[maxn], dist[maxn];
bool visit[maxn];
int i, prev, j, k;
for (i = ; i < n; i++)
node[i] = i;
while (n > ) {
int maxj = ;
for (i = ; i < n; i++) { //初始化到已圈集合的割大小
dist[node[i]] = mat[node[]][node[i]];
if (dist[node[i]] > dist[node[maxj]])
maxj = i;
}
prev = ;
memset(visit, false, sizeof (visit));
visit[node[]] = true;
for (i = ; i < n; i++) {
if (i == n - ) {
//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 = ; 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
continue;
}
visit[node[maxj]] = true;
prev = maxj;
maxj = -;
for (j = ; 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 == - || dist[node[maxj]] < dist[node[j]])
maxj = j;
}
} }
return;
}
int main() {
int n, m, a, b, v;
while (scanf("%d%d", &n, &m) != EOF) {
res = ( << );
memset(mat, , sizeof (mat));
while (m--) {
scanf("%d%d%d", &a, &b, &v);
mat[a][b] += v;
mat[b][a] += v;
}
Mincut(n);
printf("%d\n", res);
}
return ;
}