【Vijos1412】多人背包（背包DP）

题意：求0/1背包的前K优解总和

k<=50 v<=5000 n<=200

思路：日常刷水

归并即可，不用排序

 const oo=;
 var dp:array[..,..,..]of longint;
     w,c,a,b:array[..]of longint;
     n,m,k1,i,j,k,x,y,ans,v:longint;

 begin
  assign(input,'data.in'); reset(input);
  assign(output,'Tyvj1412.out'); rewrite(output);
  readln(k1,m,n);
  for i:= to n do read(w[i],c[i]);
  fillchar(dp[v],sizeof(dp[v]),$cf);
  dp[,,]:=;
  for i:= to n do
  begin
   v:=-v; dp[v]:=dp[-v];
   dp[v,,]:=;
   for j:=w[i] to m do
   begin
    for k:= to k1 do a[k]:=dp[-v,j,k];
    for k:= to k1 do b[k]:=dp[-v,j-w[i],k]+c[i];
    x:=; y:=;
    for k:= to k1 do
    begin
     if (a[x]<)and(b[y]<) then begin dp[v,j,k]:=-oo; continue; end;
     if a[x]>b[y] then begin dp[v,j,k]:=a[x]; inc(x); end
      else begin dp[v,j,k]:=b[y]; inc(y); end;
    end;
   end;
  end;
  for i:= to k1 do
   if dp[v,m,i]>= then ans:=ans+dp[v,m,i]
    else break;
  writeln(ans);
  close(input);
  close(output);
 end.