poj 1273 Drainage Ditches 夜

http://poj.org/problem?id=1273
#include<iostream>
#include<cmath>
#include<string>
#include<algorithm>
#include<queue>
#include<cstring>
#include<cstdio>

using namespace std;
const int MAX=2000000005;
const int N=205;
int h[N];
int flow[N][N];

int Bfs(int n)
{
    memset(h,0,sizeof(h));
    queue<int>str;
    str.push(1);
    h[1]=1;
    while(!str.empty())
    {
        int k=str.front();
        str.pop();
        for(int i=1;i<=n;++i)
        {
            if(h[i]==0&&flow[k][i]>0)
            {
                h[i]=h[k]+1;
                str.push(i);
            }
        }
    }
    return h[n];
}
int end;
int Add(int x,int M)
{
    if(x==end)
    return M;
    int sum=M;
    for(int i=1;i<=end;++i)
    {
        if(flow[x][i]>0&&h[i]==h[x]+1)
        {
            int w=Add(i,min(sum,flow[x][i]));
            sum=sum-w;
            flow[x][i]-=w;
            flow[i][x]+=w;
            if(sum==0)
            break;
        }
    }
    return (M-sum);
}
int main()
{
    int n,m;
    while(cin>>n>>m)
    {
        end=m;
        memset(flow,0,sizeof(flow));
        while(n--)
        {
            int i,j,k;
            cin>>i>>j>>k;
            flow[i][j]+=k;
        }
        int ans=0;
        while(Bfs(m))
        {
           ans+=Add(1,MAX);
        }
        cout<<ans<<endl;
    }
    return 0;
}