【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=800000000;
var dp:array[0..1,0..5000,1..50]of longint;
    w,c,a,b:array[1..200]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:=1 to n do read(w[i],c[i]);
 fillchar(dp[v],sizeof(dp[v]),$cf);
 dp[0,0,1]:=0;
 for i:=1 to n do
 begin
  v:=1-v; dp[v]:=dp[1-v];
  dp[v,0,1]:=0;
  for j:=w[i] to m do
  begin
   for k:=1 to k1 do a[k]:=dp[1-v,j,k];
   for k:=1 to k1 do b[k]:=dp[1-v,j-w[i],k]+c[i];
   x:=1; y:=1;
   for k:=1 to k1 do
   begin
    if (a[x]<0)and(b[y]<0) 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:=1 to k1 do
  if dp[v,m,i]>=0 then ans:=ans+dp[v,m,i]
   else break;
 writeln(ans);
 close(input);
 close(output);
end.