最小费用最大流即可。-=a[t] 写成了-=-a[t],于是为此找了很久的错QAQsading

#include
     
      #include
      
       #include
       
        #include
        
         #include
         
          using namespace std;#define rep(i,n) for(int i=1;i<=n;i++)#define clr(x,c) memset(x,c,sizeof(x))#define REP(i,s,t) for(int i=s;i<=t;i++)#define qwq(x) for(edge*e=head[x];e;e=e->next)const int nmax=55;const int inf=0x3f3f3f3f;int x;char c;int read(){	x=0;c=getchar();bool f=true;	while(!isdigit(c)){		if(c=='-') f=false; c=getchar();	}	while(isdigit(c)) x=x*10+c-'0',c=getchar();	return f?x:-x;}struct edge{	int to,cap,cost;edge *next,*rev;};edge edges[nmax<<3],*pt,*head[nmax],*p[nmax];void add(int u,int v,int d,int w){	pt->to=v;pt->cap=d;pt->cost=w;pt->next=head[u];head[u]=pt++;}void adde(int u,int v,int d,int w){	add(u,v,d,w);add(v,u,0,-w);head[u]->rev=head[v];head[v]->rev=head[u];}int d[nmax],a[nmax];bool inq[nmax];int mincost(int s,int t){	int flow=0,cost=0;	while(1){		clr(inq,0);clr(d,0x3f);d[s]=0;inq[s]=1;a[s]=inf;		queue
          
           q;q.push(s); while(!q.empty()){ int x=q.front();q.pop();inq[x]=0; qwq(x) if(e->cap>0&&d[e->to]>d[x]+e->cost){ int to=e->to; d[to]=d[x]+e->cost; a[to]=min(a[x],e->cap);p[to]=e; if(!inq[to]) q.push(to),inq[to]=1; } } if(d[t]==inf) break; flow+=a[t];cost+=d[t]*a[t]; int x=t; while(x!=s) p[x]->cap-=a[t],p[x]->rev->cap+=a[t],x=p[x]->rev->to; // printf("%d %d %d\n",d[t],flow,cost); } return cost;}int main(){ int n=read(),m=read(),v=read(); int s=0,t=n+1,tmp; pt=edges;clr(head,0); rep(i,n) tmp=read(),adde(i,t,tmp,0); rep(i,n) tmp=read(),adde(s,i,inf,tmp); rep(i,n-1) adde(i,i+1,v,m); /*REP(i,0,n+1){ qwq(i) printf("%d %d %d ",e->to,e->cap,e->cost); printf("\n"); }*/ printf("%d\n",mincost(s,t)); return 0;}
          
         
        
       
      
     

2424: [HAOI2010]订货

Time Limit: 10 Sec  Memory Limit: 128 MB

Submit: 809  Solved: 564

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Description

某公司估计市场在第i个月对某产品的需求量为Ui，已知在第i月该产品的订货单价为di，上个月月底未销完的单位产品要付存贮费用m，假定第一月月初的库存量为零，第n月月底的库存量也为零，问如何安排这n个月订购计划，才能使成本最低？每月月初订购，订购后产品立即到货，进库并供应市场，于当月被售掉则不必付存贮费。假设仓库容量为S。

Input

第1行：n, m, S (0<=n<=50, 0<=m<=10, 0<=S<=10000)

第2行：U1 , U2 , ... , Ui , ... , Un (0<=Ui<=10000)

第3行：d1 , d2 , ..., di , ... , dn (0<=di<=100)

Output

只有1行，一个整数，代表最低成本

 

Sample Input

3 1 1000

2 4 8

1 2 4

Sample Output

34

HINT

 

Source

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