P3440 [POI2006]SZK-Schools（费用流）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
inline int Abs(int a){return a<0?-a:a;}
#define N 5005
#define W 500005
int n,m,S,T,tF,tC,a[N],d[N],p[N]; bool inh[N];
int cnt=1,hd[N],nxt[W],ed[N],poi[W],val[W],cst[W];
queue <int> h;
inline void adde(int x,int y,int v1,int v2){
    nxt[ed[x]]=++cnt, hd[x]=hd[x]?hd[x]:cnt,
    ed[x]=cnt, poi[cnt]=y, val[cnt]=v1, cst[cnt]=v2;
}
inline void link(int x,int y,int v1,int v2){adde(x,y,v1,v2),adde(y,x,0,-v2);}
bool bfs(){
    memset(d,63,sizeof(d)); int inf=d[0];
    h.push(S); a[S]=inf; d[S]=0; inh[S]=1;
    while(!h.empty()){
        int x=h.front(); h.pop(); inh[x]=0;
        for(int i=hd[x];i;i=nxt[i]){
            int to=poi[i];
            if(val[i]>0&&d[to]>d[x]+cst[i]){
                d[to]=d[x]+cst[i]; p[to]=i;
                a[to]=min(a[x],val[i]);
                if(!inh[to]) h.push(to),inh[to]=1;
            }
        }
    }if(d[T]==inf) return 0;
    tF+=a[T]; tC+=a[T]*d[T];
    for(int i=T;i!=S;i=poi[p[i]^1])
        val[p[i]]-=a[T],val[p[i]^1]+=a[T];
    return 1;
}
int main(){
    scanf("%d",&n); int id,l,r,c;
    S=n*2+1; T=S+1;
    for(int i=1;i<=n;++i) link(S,i,1,0);
    for(int i=n+1;i<=n+n;++i) link(i,T,1,0);
    for(int i=1;i<=n;++i){
        scanf("%d%d%d%d",&id,&l,&r,&c);
        for(int j=l;j<=r;++j)
            link(i,j+n,1,c*Abs(id-j));
    }while(bfs());
    if(tF<n) puts("NIE");
    else printf("%d",tC);
    return 0;
}