Bashu2445 -- 【网络流24题-10】餐巾问题

#include<cstdio>
#include<cmath>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<queue>
using namespace std;
const int maxn=2100,maxm=110000,inf=0x7fffffff;
int n,m,p,f,ss,tt,a,b,s,t,mincost,tot=1,head[maxn],d[maxn],from[maxm*2];
queue<int> q;
bool v[maxn];
struct node{
    int from,go,v,c,next;
}e[maxm*2];
inline int read(){
    int x=0;char ch=getchar();
    while (ch<‘0‘ || ch>‘9‘) ch=getchar();
    while (ch>=‘0‘ && ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x;
}
inline void addedge(int x,int y,int v,int c){
    e[++tot]=(node){x,y,v,c,head[x]};head[x]=tot;
    e[++tot]=(node){y,x,0,-c,head[y]};head[y]=tot;
}
bool spfa(){
    for (int i=s;i<=t;i++) v[i]=0,d[i]=inf;
    q.push(s);d[s]=0;v[s]=1;
    while (!q.empty()){
        int x=q.front();q.pop();v[x]=0;
        for (int i=head[x],y;i;i=e[i].next){
            if (e[i].v && d[x]+e[i].c<d[y=e[i].go]){
                d[y]=d[x]+e[i].c;from[y]=i;
                if (!v[y]) v[y]=1,q.push(y);
            }
        }
    }
    return d[t]!=inf;
}
void mcf(){
    mincost=0;
    while(spfa()){
        int tmp=inf;
        for (int i=from[t];i;i=from[e[i].from]) tmp=min(tmp,e[i].v);
        mincost+=tmp*d[t];
        for (int i=from[t];i;i=from[e[i].from]) e[i].v-=tmp,e[i^1].v+=tmp;
    }
}
int main(){
    scanf("%d%d%d%d%d%d",&n,&p,&m,&f,&tt,&ss);
    s=0;t=n+n+1;
    for (int i=1;i<=n;i++){
        a=read();
        addedge(s,i,a,0);
        addedge(n+i,t,a,0);
        addedge(s,n+i,inf,p);
        if (i<n) addedge(i,i+1,inf,0);
        if (i+m<=n) addedge(i,n+m+i,inf,f);
        if (i+tt<=n) addedge(i,n+i+tt,inf,ss);
    }
    mcf();
    printf("%d\n",mincost);
}