HDU 1532 最大流，EK算法

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<queue>
#define N 205
#define INF 0x7fffffff
#define M 505
using namespace std;
int head
,cnt;
struct edge{
    int to,next,cap;
}e[M];
void init(){
    cnt=0;
    memset(head,-1,sizeof(head));
}
void addedge(int u,int v,int cap){
    e[cnt].to=v;e[cnt].cap=cap;e[cnt].next=head[u];head[u]=cnt++;
    e[cnt].to=u;e[cnt].cap=0;e[cnt].next=head[v];head[v]=cnt++;
}
int pre
,pe
;
queue<int> q;
int EK(int s,int t){
    int max_flow=0;
    while(true){
        while(!q.empty()){
            q.pop();
        }
        memset(pre,-1,sizeof(pre));
        q.push(s);
        while(!q.empty()){
            int u=q.front();
            q.pop();
            for(int i=head[u];i!=-1;i=e[i].next){
                int v=e[i].to;
                if(pre[v]==-1&&e[i].cap>0){
                    q.push(v);
                    pre[v]=u;
                    pe[v]=i;
                }

            }
            if(pre[t]!=-1)
            break;

        }
        if(pre[t]==-1)
        break;
        int aug=INF;
        for(int v=t;v!=s;v=pre[v]){
            aug=min(aug,e[pe[v]].cap);
        }
        for(int v=t;v!=s;v=pre[v]){
            e[pe[v]].cap-=aug;
            e[pe[v]^1].cap+=aug;
        }
        max_flow+=aug;
    }

    return max_flow;
}
int main()
{
    int n,m,u,v,cap,ans;
    while(~scanf("%d%d",&m,&n)){
        init();
        while(m--){
            scanf("%d%d%d",&u,&v,&cap);
            addedge(u,v,cap);
        }
        ans=EK(1,n);
        printf("%d\n",ans);
    }
    return 0;
}