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[..] of longint;
     f:array[..,..] 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:=;
  for i:= to n do readln(ap[i],bp[i],as[i],bs[i]);
  end;
 procedure main;
  begin
  fillchar(f,sizeof(f),);
  f[,]:=;
  for i:= to n do
   begin
    for j:= to as[i] do f[i,j]:=-j*ap[i];
    for j:= to as[i] do
     f[i,j]:=max(f[i,j],f[i-,j]);
    t:=i-w-;
    if t>= then
     begin
      head:=;tail:=;
      for j:= 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-]) 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:=;tail:=;
      for j:=maxp downto  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-]) 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,]);
    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[..] of ji;
   f:array[-..,..] 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:= to maxp do
       f[i,j]:=-;
   for i:= to t do
     begin
       readln(api,bpi,asi,bsi);
       head:=;
       tail:=;
       f[i]:=f[i-];
       q[].s:=;
       q[].w:=f[i-w-,];
       for j:= to maxp do
         begin
           inc(tail);
           q[tail].w:=f[i-w-,j]+j*api;
           q[tail].s:=j;
           while (head<tail)and(q[tail-].w<q[tail].w) do
             begin
               q[tail-]:=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:=;
       tail:=;
       q[].s:=maxp;
       q[].w:=f[i-w-,maxp]+maxp*bpi;
       for j:=maxp- downto  do
         begin
           inc(tail);
           q[tail].w:=f[i-w-,j]+j*bpi;
           q[tail].s:=j;
           while (head<=tail)and(q[tail].w<x) do
             begin
               q[tail-]:=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,]);
 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……