请求加强数据

蒟蒻反向边没加都 A 了。

Code：

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<set>
#include<cmath>
using namespace std;

typedef long long LL;
const LL MAXN=505,MAXM=1e4+50,INF=0x3f3f3f3f3f3f3f3f;

struct edge{
    LL nxt;
    LL to;
    LL cap;
    LL flow;
};

LL N,M,s,t,dis[MAXN],Ans=0;
edge e[MAXM<<1];
LL head[MAXN],now[MAXN],Cnte=1;
queue<LL> q;

void adde(LL u,LL v,LL w){
    ++Cnte;
    e[Cnte].to=v;
    e[Cnte].cap=w;
    e[Cnte].nxt=head[u];
    head[u]=Cnte;
}

bool bfs(){
    for(int i=1;i<=N;++i) dis[i]=INF;
    while(!q.empty()) q.pop();
    q.push(s);
    dis[s]=0;
    while(!q.empty()){
        LL u=q.front();
        q.pop();
        now[u]=head[u];
        for(int i=head[u];i;i=e[i].nxt){
            LL v=e[i].to;
            if(e[i].cap>e[i].flow&&dis[u]+1<dis[v]){
                dis[v]=dis[u]+1;
                q.push(v);
            }
        }
    }
    return dis[t]!=INF;
}

LL dfs(LL u,LL flow){
    if(flow==0||u==t) return flow;
    LL res=0;
    for(int i=now[u];i;i=e[i].nxt){
        now[u]=i;
        LL v=e[i].to;
        if(dis[v]==dis[u]+1&&e[i].cap>e[i].flow){
            LL t=dfs(v,min(e[i].cap-e[i].flow,flow));
            if(!t) continue;
            e[i].flow+=t;
            //e[i^1].flow-=t;
            res+=t;
            flow-=t;
            if(flow==0) break;
        }
    }
    if(res==0) dis[u]=INF;
    return res;
}

LL Dinic(){
    LL res=0;
    while(bfs()) res+=dfs(s,INF);
    return res;
}

void Init(){
    scanf("%lld%lld%lld%lld",&N,&M,&s,&t);
    for(int i=1;i<=M;++i){
        LL u,v,w;
        scanf("%lld%lld%lld",&u,&v,&w);
        adde(u,v,w);//adde(v,u,0);
    }
}

void Solve(){
    Ans=Dinic();
}

void Print(){
    printf("%lld\n",Ans);
}

int main(){
    Init();
    Solve();
    Print();
    return 0;
}