POJ 1273 一般性預流推進

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;

#define MIN(a,b) (a)<(b)?(a):(b)

int m,n;
int flow[202][202];
int cap[202][202];
int e[202];
int h[202];

void fun()
{
	//Init
	memset(flow,0,sizeof(flow));
	memset(e,0,sizeof(e));
	memset(h,0,sizeof(h));
	h[1]=n;
	for(int i=2;i<=n;i++)
	{
		if(cap[1][i]>0)
		{
			flow[1][i]=cap[1][i];
			flow[i][1]=-flow[1][i];
			e[i]=cap[1][i];
			e[1]-=e[i];
		}
	}
	//Init
	while(1)
	{
		bool empty=1;
		int i;
		for(i=2;i<n;i++)
		{
			if(e[i]>0)
			{
				empty=0;
				bool push=0;
				for(int j=0;j<=n;j++)
				{
					if(cap[i][j]>flow[i][j]&&h[i]==h[j]+1)
					{
						push=1;
						int d=MIN(cap[i][j]-flow[i][j],e[i]);
						flow[i][j]+=d;
						flow[j][i]-=d;
						e[i]-=d;
						e[j]+=d;
					}
				}
				if(!push)
				{
					int min=0x1f1f1f1f;
					for(int j=1;j<=n;j++)
					{
						if(cap[i][j]>flow[i][j]&&h[i]<h[j]+1)
						{
							min=MIN(min,h[j]);
						}
					}
					h[i]=min+1;
				}
				break;
			}
		}
		if(empty||i==n)break;
	}
}

int main()
{
	while(~scanf("%d%d",&m,&n))
	{
		memset(cap,0,sizeof(cap));
		for(int i=1;i<=m;i++)
		{
			int u,v,w;
			scanf("%d%d%d",&u,&v,&w);
			cap[u][v]+=w;
		}
		fun();
		printf("%d\n",e[n]);
	}
	return 0;
}