POJ 1293 最大流

#include<iostream>
#include<stdio.h>
#include<queue>
#include<cstring>
using namespace std;
#define INF 1000000000
#define MAXN 1000
int a[MAXN];
int cap[MAXN][MAXN],flow[MAXN][MAXN],p[MAXN];

queue<int>q;
int main()
{
    int n,m;
    while(cin>>n>>m)
    {
        memset(cap,0,sizeof(cap));
        int a1,b,c;
        for(int i=1;i<=n;i++)
        {
            cin>>a1>>b>>c;
            cap[a1][b]+=c;
        }
        int t=m;
        memset(flow,0,sizeof(flow));
        int f=0;
        int s=1;
        while(1)
        {
            memset(a,0,sizeof(a));
            a[s]=INF;
            q.push(s);
            while(!q.empty())
            {
                int u=q.front();
                q.pop();
                for(int v=1;v<=m;v++)
                if(!a[v]&&cap[u][v]>flow[u][v])
                {
                    p[v]=u;
                    q.push(v);
                    a[v]=a[u]<cap[u][v]-flow[u][v]?a[u]:cap[u][v]-flow[u][v];
                }
            }
            if(a[t]==0)
            break;
            for(int u=t;u!=s;u=p[u])
            {
                flow[p[u]][u]+=a[t];
               flow[u][p[u]]-=a[t];
            }
            f+=a[t];
        }
        printf("%d\n",f);
    }
    return 0;
}