poj 1273 Drainage Ditches(最大流的EK算法模板)

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string.h>
#include <queue>
#include <limits.h>
#define MAX 250
using namespace std;
int cap[MAX][MAX];
int m;
int EKarp(int s,int t)
{
	queue<int> Q;
	int flow[MAX][MAX],a[MAX],u,v,f,pre[MAX];
	f = 0;
	memset(flow,0,sizeof(flow));
	while(1)
	{
		Q.push(s);
		memset(a,0,sizeof(a));
		a[s] = INT_MAX;
		while( !Q.empty() )
		{
			u = Q.front();
			Q.pop();
			for(v=1; v<=m; v++)
				if( !a[v] && cap[u][v] > flow[u][v] )
				{
					Q.push(v);
					a[v] = a[u] < cap[u][v] - flow[u][v] ? a[u] : cap[u][v] - flow[u][v];
					pre[v] = u;
				}
		}
		if( a[t] == 0 )
			break;
		for(u=t; u!=s; u=pre[u])
		{
			flow[pre[u]][u] += a[t];
			flow[u][pre[u]] -= a[t];
		}
		f += a[t];
	}
	return f;
}
int main()
{
	int from,to,c,n,ans;
	while( scanf("%d%d",&n,&m) != EOF )
	{
		memset(cap,0,sizeof(cap));
		while( n-- )
		{
			scanf("%d%d%d",&from,&to,&c);
			cap[from][to] += c;
		}
		ans = EKarp(1,m);
		printf("%d/n",ans);
	}
return 0;
}