HDU4289Control 无向图拆点最大流

/*
**  无向图拆点，求最大流，最大流即为割点个数。
*/
#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>
using namespace std;
const int maxn = 410;
const int maxm = 100100;
const int INF = 200000000;
struct node{
    int v,flow,next;
}edge[maxm];
int head[maxn],dis[maxn],aug[maxn];
int n,m,s,t,id;
void add_edge(int u,int v,int flow){
    edge[id].v = v;edge[id].flow = flow;edge[id].next = head[u];head[u] = id++;
    edge[id].v = u;edge[id].flow = 0   ;edge[id].next = head[v];head[v] = id++;
}
void init(){
    int cost,u,v;
    memset(head,-1,sizeof(head));id = 0;
    for(int i = 1; i <= n; i++){
        scanf("%d",&cost);
        add_edge(i,i+n,cost);
    }
    //v入，v+n出
    while( m-- ){
        scanf("%d%d",&u,&v);
        add_edge(u+n,v,INF);
        add_edge(v+n,u,INF);
    }
    add_edge(0,s,INF);
    add_edge(t+n,n*2+1,INF);
    s = 0,t = n*2+1;
}
bool bfs(){
    memset(dis,-1,sizeof(dis));
    queue<int>que;
    dis[s] = 0;
    que.push(s);
    while(!que.empty()){
        int u = que.front();
        que.pop();
        for(int id = head[u]; id != -1; id = edge[id].next){
            int v = edge[id].v;
            if( edge[id].flow > 0 && dis[v] == -1){
                dis[v] = dis[u] + 1;
                que.push(v);
            }
        }
    }
    return dis[t] != -1;
}
int min(int x,int y){
    return x < y ? x : y;
}
int dinic(int u,int flow){
    if(u == t || flow == 0)return flow;
    int tmp = flow;
    for(int id = head[u]; id != -1; id = edge[id].next){
        int v = edge[id].v;
        if( edge[id].flow > 0 && dis[v] == dis[u] + 1){
            int tt = dinic(v,min(tmp,edge[id].flow));
            tmp -= tt;
            edge[id].flow -= tt;
            edge[id^1].flow += tt;
            if(tmp == 0) break;
        }
    }
    return flow - tmp;
}
int main(){
    //freopen("in.txt","r",stdin);
    while(~scanf("%d%d",&n,&m)){
        scanf("%d%d",&s,&t);
        init();
       // cout << id << endl;
        int max_flow = 0;
        while(bfs())
            max_flow += dinic(s,INF);
        printf("%d
",max_flow);
    }
    return 0;
}