bzoj2879: [Noi2012]美食节

#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<queue>
using namespace std;
#define rep(i,s,t) for(int i=s;i<=t;i++)
#define dwn(i,s,t) for(int i=s;i>=t;i--)
#define clr(x,c) memset(x,c,sizeof(x))
#define qwq(x) for(edge *o=head[x];o;o=o->next)
int read(){
    int x=0;char c=getchar();
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
    return x;
}
const int nmax=2e3+5;
const int maxn=1e6+5;
const int inf=0x7f7f7f7f;
struct edge{
    int to,cap,cost;edge *next,*rev;
};
edge es[maxn],*pt=es,*head[nmax],*p[nmax],*t[nmax];
int b[nmax],map[45][105],dis[nmax],num[nmax];bool inq[nmax];
void add(int u,int v,int d,int c){
    pt->to=v;pt->cap=d;pt->cost=c;pt->next=head[u];head[u]=pt++;
    pt->to=u;pt->cap=0;pt->cost=-c;pt->next=head[v];head[v]=pt++;
    head[u]->rev=head[v];head[v]->rev=head[u];
}
queue<int>q;
bool mcmf(int s,int t,int &ans){
    clr(dis,0x7f);clr(inq,0);dis[s]=0;inq[s]=1;q.push(s);
    while(!q.empty()){
        int x=q.front();q.pop();inq[x]=0;
        qwq(x) if(o->cap>0&&dis[o->to]>dis[x]+o->cost){
            int to=o->to;dis[to]=dis[x]+o->cost;p[to]=o;
            if(!inq[to]) q.push(to),inq[to]=1;
        }
    }
    if(dis[t]==inf) return 0;
    ans+=dis[t];
    int x=t;
    while(x!=s) p[x]->cap--,p[x]->rev->cap++,x=p[x]->rev->to;
    return 1;
}
int main(){
    int n=read(),m=read(),sm=0,u,v,d;
    rep(i,1,n) b[i]=read(),sm+=b[i];
    int s=n+m+sm+1,T=s+1;
    rep(i,1,n) rep(j,1,m) map[i][j]=read();
    rep(i,1,n) add(s,i,b[i],0);
    rep(i,1,m){
        add(n+i,T,1,0);num[i]=1;t[i]=pt-1;
        rep(j,1,n) add(j,n+i,1,map[j][i]);
    }
    int cnt=n+m,ans=0;
    while(mcmf(s,T,ans)){
        for(u=1;u<=m&&!t[u]->cap;++u);
        ++num[u];++cnt;
        add(cnt,T,1,0);t[u]=pt-1;
        rep(i,1,n) add(i,cnt,1,num[u]*map[i][u]);
    }
    printf("%d\n",ans);
    return 0;
}