poj 2914 Minimum Cut 无向图最小边割

//poj 2914
//sep9
#include <iostream>
using namespace std;
const int maxN=512;
int g[maxN][maxN];
int b[maxN],dist[maxN];
int n,m;

int Min_Cut_Phase(int ph,int &x,int &y)
{
	int i,j,t;
	t=1;
	b[1]=ph;
	for(i=1;i<=n;++i)
		if(b[i]!=ph) dist[i]=g[1][i];			
	for(i=1;i<n;++i){
		x=t;
		for(t=0,j=1;j<=n;++j)
			if(b[j]!=ph&&(!t||dist[j]>dist[t]))
				t=j;
		b[t]=ph;
		for(j=1;j<=n;++j)
			if(b[j]!=ph) dist[j]+=g[t][j];	
	}
	return y=t,dist[t];	
}

void Merge(int x,int y)
{
	int i;
	if(x>y) swap(x,y);
	for(i=1;i<=n;++i)
		if(i!=x&&i!=y)
			g[i][x]+=g[i][y],g[x][i]+=g[y][i];
	if(y==n)
		return ;
	for(i=1;i<n;++i) if(i!=y){
		swap(g[i][y],g[i]
);
		swap(g[y][i],g
[i]);
	}
	return ;					
}

int main()
{
	while(scanf("%d%d",&n,&m)==2){
		memset(g,0,sizeof(g));
		while(m--){
			int a,b,c;
			scanf("%d%d%d",&a,&b,&c);
			++a,++b;
			g[a][b]+=c;
			g[b][a]+=c;
		}
		int ret=INT_MAX,i,x,y;
		memset(b,0,sizeof(b));
		for(i=1;n>1;++i,--n){
			ret=min(ret,Min_Cut_Phase(i,x,y));
			Merge(x,y);	
		}
		printf("%d\n",ret);
	}
	return 0;	
}