SCOI2010 and SXOI2014 股票交易（DP）

明显的单调队列……

但下面的程序一直有bug

附上题解：http://blog.csdn.net/njlcazl/article/details/8611042

附上我的代码：

var head,tail,i,n,maxp,w,t,ans,j:longint;
    as,bs,ap,bp,q,val:array[0..2020] of longint;
    f:array[0..2020,0..2020] of longint;
function max(x,y:longint):longint;
 begin
 if x>y then exit(x) else exit(y);
 end;
procedure init;
 begin
 readln(n,maxp,w);ans:=0;
 for i:=1 to n do readln(ap[i],bp[i],as[i],bs[i]);
 end;
procedure main;
 begin
 fillchar(f,sizeof(f),128);
 f[0,0]:=0;
 for i:=1 to n do
  begin
   for j:=0 to as[i] do f[i,j]:=-j*ap[i];
   for j:=0 to as[i] do
    f[i,j]:=max(f[i,j],f[i-1,j]);
   t:=i-w-1;
   if t>=0 then
    begin
     head:=0;tail:=0;
     for j:=0 to maxp do
      begin
       while (head<tail) and (q[head]<j-as[i]) do inc(head);
       while (head<tail) and (f[t,j]+j*ap[i]>=val[tail-1]) do dec(tail);
       val[tail]:=f[t,j]+j*ap[i];
       q[tail]:=j;inc(tail);
       if head<tail then f[i,j]:=max(f[i,j],val[head]-j*ap[i]);
      end;
     head:=0;tail:=0;
     for j:=maxp downto 0 do
      begin
       while (head<tail) and (q[head]>j+bs[i]) do inc(head);
       while (head<tail) and (f[t,j]+j*bp[i]>=val[tail-1]) do dec(tail);
       val[tail]:=f[t,j]+j*bp[i];
       q[tail]:=j;inc(tail);
       if head<tail then f[i,j]:=max(f[i,j],val[head]-j*bp[i]);
      end;
     end;
    ans:=max(ans,f[i,0]);
   end;
 writeln(ans);
 end;
begin
 init;
 main;
end.                                          

还有另一位oier的代码：

type
  ji=record
  w,s:longint;
end;
var
  q:array[0..2005] of ji;
  f:array[-2000..2000,0..2000] of longint;
  x,i,j,k,head,tail,t,maxp,w,api,bpi,asi,bsi:longint;

function max(x,y:longint):longint;
begin
  if x>y then exit(x);
  exit(y);
end;

begin
  readln(t,maxp,w);
  for i:=-t to t do
    for j:=1 to maxp do
      f[i,j]:=-1000000000;
  for i:=1 to t do
    begin
      readln(api,bpi,asi,bsi);
      head:=1;
      tail:=1;
      f[i]:=f[i-1];
      q[1].s:=0;
      q[1].w:=f[i-w-1,0];
      for j:=1 to maxp do
        begin
          inc(tail);
          q[tail].w:=f[i-w-1,j]+j*api;
          q[tail].s:=j;
          while (head<tail)and(q[tail-1].w<q[tail].w) do
            begin
              q[tail-1]:=q[tail];
              dec(tail);
            end;
          while (head<=tail)and(q[tail].s<j-asi) do inc(head);
          f[i,j]:=max(f[i,j],q[head].w-api*j);
        end;
      head:=1;
      tail:=1;
      q[1].s:=maxp;
      q[1].w:=f[i-w-1,maxp]+maxp*bpi;
      for j:=maxp-1 downto 0 do
        begin
          inc(tail);
          q[tail].w:=f[i-w-1,j]+j*bpi;
          q[tail].s:=j;
          while (head<=tail)and(q[tail].w<x) do
            begin
              q[tail-1]:=q[tail];
              dec(tail);
            end;
          while (head<=tail)and(q[head].s>j+bsi) do inc(head);
          f[i,j]:=max(f[i,j],q[head].w-j*bpi);
        end;
    end;
  writeln(f[t,0]);
end.                               

这两种代码方法是一样的，但求解的过程不一样，可以挑选自己喜欢的来写。

ps：这两个代码都有bug，在bzoj上都是wa……