bzoj2424

比较简单的费用流，一目了然

 const inf=;
 type node=record
        next,point,flow,cost:longint;
      end;

 var edge:array[..] of node;
     q:array[..] of longint;
     p,d,pre,cur,u,w:array[..] of longint;
     v:array[..] of boolean;
     s,i,len,n,m,t:longint;

 function min(a,b:longint):longint;
   begin
     if a>b then exit(b) else exit(a);
   end;

 procedure add(x,y,f,c:longint);
   begin
     inc(len);
     edge[len].point:=y;
     edge[len].flow:=f;
     edge[len].cost:=c;
     edge[len].next:=p[x];
     p[x]:=len;
   end;

 function spfa:boolean;
   var y,i,f,r,x:longint;
   begin
     d[]:=;
     for i:= to t do
       d[i]:=inf;
     f:=;
     r:=;
     q[]:=;
     fillchar(v,sizeof(v),false);
     v[]:=true;
     while f<=r do
     begin
       x:=q[f];
       v[x]:=false;
       i:=p[x];
       while i<>- do
       begin
         y:=edge[i].point;
         if edge[i].flow> then
           if d[y]>d[x]+edge[i].cost then
           begin
             d[y]:=d[x]+edge[i].cost;
             pre[y]:=x;
             cur[y]:=i;
             if not v[y] then
             begin
               inc(r);
               q[r]:=y;
               v[y]:=true;
             end;
           end;
         i:=edge[i].next;
       end;
       inc(f);
     end;
     if d[t]=inf then exit(false) else exit(true);
   end;

 function mincost:longint;
   var neck,i,j:longint;
   begin
     mincost:=;
     while spfa do
     begin
       neck:=inf;
       i:=t;
       while i<> do
       begin
         j:=cur[i];
         neck:=min(neck,edge[j].flow);
         i:=pre[i];
       end;
       i:=t;
       while i<> do
       begin
         j:=cur[i];
         dec(edge[j].flow,neck);
         inc(edge[j xor ].flow,neck);
         i:=pre[i];
       end;
       mincost:=mincost+d[t]*neck;
     end;
   end;

 begin
   len:=-;
   fillchar(p,sizeof(p),);
   readln(n,m,s);
   t:=n+;
   for i:= to n do
     read(u[i]);
   for i:= to n do
   begin
     read(w[i]);
     add(,i,inf,w[i]);
     add(i,,,-w[i]);
     add(i,t,u[i],);
     add(t,i,,);
     if i<>n then
     begin
       add(i,i+,s,m);
       add(i+,i,,-m);
     end;
   end;
   writeln(mincost);
 end.