zkw费用流+当前弧优化

var
  o,v:array[0..1600] of boolean;
  f,s,d,dis:array[0..1600] of longint;
  next,p,c,w:array[-100000..100000] of longint;
  i,j,k,l,y,t,ss,tt,n,ans,imp,flow:longint;
procedure link(i,j,k,l:longint);
begin
  inc(t);
  next[t]:=d[i]; d[i]:=t; p[t]:=j; c[t]:=k; w[t]:=l;
  next[-t]:=d[j]; d[j]:=-t; p[-t]:=i; w[-t]:=-l;
end;
function dfs(i,flow:longint):longint;
var j,k,l,min:longint;
begin
  if i=tt then
  begin
    inc(ans,dis[i]*flow); exit(flow);
  end;
  k:=s[i]; j:=p[k]; dfs:=0;
  o[i]:=true; v[i]:=true;
  while k<>0 do
  begin
    l:=dis[i]+w[k]-dis[j]; min:=flow;
    if c[k]<min then min:=c[k];
    if(min>0)and(l<f[j])then f[j]:=l;
    if(min>0)and(l=0)and(not o[j])then
    begin
      l:=dfs(j,min);
      inc(dfs,l); dec(flow,l);
      dec(c[k],l); inc(c[-k],l);
    end;
    if flow=0 then break;
    s[i]:=next[s[i]];
    k:=s[i]; j:=p[k];
  end;
  o[i]:=false;
end;
begin
  build;
  repeat
    for i:=ss to tt do s[i]:=d[i];
    fillchar(v,sizeof(v),false);
    fillchar(f,sizeof(f),1);
    inc(flow,dfs(ss,1 shl 20));
    imp:=1 shl 20;
    for i:=ss to tt do
    if(not v[i])and(f[i]<imp)then imp:=f[i];
    for i:=ss to tt do if not v[i] then inc(dis[i],imp);
  until imp=1 shl 20;
  writeln(ans);
end.