[AHOI2014/JSOI2014]支线剧情

裸的上下界费用流。。。

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<queue>
#include<stack>
#include<set>
#include<bitset>
#include<sstream>
#include<cstdlib>
#define QAQ int
#define TAT long long
#define OwO bool
#define ORZ double
#define Ug unsigned
#define F(i,j,n) for(QAQ i=j;i<=n;++i)
#define E(i,j,n) for(QAQ i=j;i>=n;--i)
#define MES(i,j) memset(i,j,sizeof(i))
#define MEC(i,j) memcpy(i,j,sizeof(j))

using namespace std;
const QAQ N=505,M=5000000;
const QAQ oo=1e8;

QAQ n,m,s,t;
struct Link{
    QAQ to,last,rem,val,from;
}a[M];
QAQ head[N],js=1,ans;
QAQ dis[N];
OwO vis[N];
queue<QAQ> q;

void add(QAQ x,QAQ y,QAQ z,QAQ w){
    a[++js].from=x;a[js].to=y;
    a[js].rem=z;a[js].val=w;
    a[js].last=head[x];head[x]=js;
}

void Insert(QAQ x,QAQ y,QAQ z,QAQ w){
    add(x,y,z,w);add(y,x,0,-w);
}


OwO spfa(QAQ s,QAQ t){
    F(i,s,t) dis[i]=oo,vis[i]=0;
    dis[t]=0;vis[t]=1;
    q.push(t);
    while(!q.empty()){
        QAQ x=q.front();q.pop();vis[x]=0;
        for(QAQ i=head[x];i;i=a[i].last) if(a[i^1].rem&&dis[a[i].to]>dis[x]-a[i].val){
            dis[a[i].to]=dis[x]-a[i].val;
            if(!vis[a[i].to]) vis[a[i].to]=1,q.push(a[i].to);
        }
    }
    return dis[s]<oo;
}

QAQ dfs(QAQ x,QAQ want){
    if(x==t||!want) {
//        vis[x]=1;
        return want;
    }
    QAQ f=0;
    vis[x]=1;
    for(QAQ i=head[x];i;i=a[i].last) if(!vis[a[i].to]&&a[i].rem&&dis[a[i].to]==dis[x]-a[i].val){
        QAQ d=dfs(a[i].to,min(want-f,a[i].rem));
        if(d){
            ans+=d*a[i].val;
            a[i].rem-=d;
            a[i^1].rem+=d;
            f+=d;
        }
        if(f==want) break;
    }
    vis[x]=0;
    return f;
}

void zkw(){
//    QAQ ans=0;
    while(spfa(s,t)){
        vis[t]=1;
        while(vis[t]){
            MES(vis,0);
            dfs(s,oo);
        }
    }
//    return ans;
}


QAQ main(){
    scanf("%d",&n);
    s=0;t=n+1;
    F(i,1,n){
        QAQ k;
        scanf("%d",&k);
        if(k) Insert(i,t,k,0);
        if(i!=1) Insert(i,1,oo,0);
        while(k--){
            QAQ v,w;
            scanf("%d%d",&v,&w);
            Insert(s,v,1,w);
            Insert(i,v,oo,w);
        }
    }
    zkw();
    printf("%d\n",ans);
    return 0;
}