hdu3549最大流

这应该是最裸的最大流题了吧，刚开始学最大流，拿来练练手。从源点到汇点的最大流，EK算法实现如下，不再多说：http://acm.hdu.edu.cn/showproblem.php?pid=3549

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

#define INS 0xfffffff
#define MAX 105

int map[MAX][MAX],f[MAX];
int r[MAX];
bool vis[MAX];
int m,n;

bool bfs(){
    int start,end,size,begin = 0;
    start = end = 0; size = 100;
    memset(vis,false,sizeof(vis));
    r[start] = 1; int k = 1;
    while(start <= end){ 
        vis[ r[start] ] = true;
        for(int i = 1;i <= n;++i){
            if(!vis[i] && map[ r[start] ][i] > 0){
                end = (end+1)%size;
                f[i] = r[start]; r[end] = i; 
                if(i == n) return true;
            }
        }
        start = (start+1)%size;
    }
    return false;
}

int E_K(){
    int d = INS,i,res = 0;
    memset(f,-1,sizeof(f));
    f[1] = 0;
    while(bfs()){ 
        i = n; d = INS;
        while(f[i] != 0){
            d = min(d,map[ f[i] ][i]);  i = f[i]; 
        }
        i = n; res += d;
        while(f[i] != 0){
            map[ f[i] ][i] -=d;
            map[i][ f[i] ] +=d;  
            i = f[i]; 
        }
        memset(f,-1,sizeof(f)); f[1] = 0;
    } return res;
}

int main()
{
    int t;
    scanf("%d",&t);
    for(int k = 1;k <= t;++k){
        scanf("%d%d",&n,&m);
        int b,e,v;
        memset(map,0,sizeof(map));
        for(int i = 0;i < m;++i){
            scanf("%d%d%d",&b,&e,&v);
            map[b][e] += v;
        }
        printf("Case %d: %d\n",k,E_K());
    }
    return 0;
｝