[网络流24题] 餐巾计划问题 (最小费用最大流)

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#include<algorithm>#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#define inf 0x7fffffffusing namespace std;inline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}struct edge{int from,to,next,v,c;}e[200001];int n,m,day,p,f,s,cnt=1,ans,T=2001,head[2005],from[2005],dis[2005];inline void ins(int u,int v,int w,int c){e[++cnt]=(edge){u,v,head[u],w,c};head[u]=cnt;e[++cnt]=(edge){v,u,head[v],0,-c};head[v]=cnt;}inline bool spfa(){int t=0,w=1,q[10001];bool inq[10001];memset(inq,0,sizeof(inq));for(int i=0;i<=T;i++)dis[i]=inf;dis[0]=0;q[0]=0;inq[0]=1;while(t!=w){int now=q[t++];if(t==T)t=0;for(int i=head[now];i;i=e[i].next)if(e[i].v&&dis[e[i].to]>dis[now]+e[i].c){dis[e[i].to]=dis[now]+e[i].c;from[e[i].to]=i;if(!inq[e[i].to]){inq[e[i].to]=1;q[w++]=e[i].to;if(w==T)w=0;}}inq[now]=0;}if(dis[T]==inf)return 0;return 1;}inline void mcf(){int x=inf;for(int i=from[T];i;i=from[e[i].from])x=min(x,e[i].v);for(int i=from[T];i;i=from[e[i].from]){e[i].v-=x;e[i^1].v+=x;ans+=e[i].c*x;}}int main(){day=read();p=read();m=read();f=read();n=read();s=read();    for(int i=1;i<=day;i++){        if(i+1<=day)ins(i,i+1,inf,0);        if(i+m<=day)ins(i,day+i+m,inf,f);        if(i+n<=day)ins(i,day+i+n,inf,s);        ins(0,day+i,inf,p);    }    for(int i=1;i<=day;i++){        int x=read();        ins(0,i,x,0);        ins(day+i,T,x,0);    }    while(spfa())mcf();    printf("%d",ans);    return 0;}

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