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：
1 var head,tail,i,n,maxp,w,t,ans,j:longint; 2 as,bs,ap,bp,q,val:array[0..2020] of longint; 3 f:array[0..2020,0..2020] of longint; 4 function max(x,y:longint):longint; 5 begin 6 if x>y then exit(x) else exit(y); 7 end; 8 procedure init; 9 begin 10 readln(n,maxp,w);ans:=0; 11 for i:=1 to n do readln(ap[i],bp[i],as[i],bs[i]); 12 end; 13 procedure main; 14 begin 15 fillchar(f,sizeof(f),128); 16 f[0,0]:=0; 17 for i:=1 to n do 18 begin 19 for j:=0 to as[i] do f[i,j]:=-j*ap[i]; 20 for j:=0 to as[i] do 21 f[i,j]:=max(f[i,j],f[i-1,j]); 22 t:=i-w-1; 23 if t>=0 then 24 begin 25 head:=0;tail:=0; 26 for j:=0 to maxp do 27 begin 28 while (head<tail) and (q[head]<j-as[i]) do inc(head); 29 while (head<tail) and (f[t,j]+j*ap[i]>=val[tail-1]) do dec(tail); 30 val[tail]:=f[t,j]+j*ap[i]; 31 q[tail]:=j;inc(tail); 32 if head<tail then f[i,j]:=max(f[i,j],val[head]-j*ap[i]); 33 end; 34 head:=0;tail:=0; 35 for j:=maxp downto 0 do 36 begin 37 while (head<tail) and (q[head]>j+bs[i]) do inc(head); 38 while (head<tail) and (f[t,j]+j*bp[i]>=val[tail-1]) do dec(tail); 39 val[tail]:=f[t,j]+j*bp[i]; 40 q[tail]:=j;inc(tail); 41 if head<tail then f[i,j]:=max(f[i,j],val[head]-j*bp[i]); 42 end; 43 end; 44 ans:=max(ans,f[i,0]); 45 end; 46 writeln(ans); 47 end; 48 begin 49 init; 50 main; 51 end.
还有另一位oier的代码：
1 type 2 ji=record 3 w,s:longint; 4 end; 5 var 6 q:array[0..2005] of ji; 7 f:array[-2000..2000,0..2000] of longint; 8 x,i,j,k,head,tail,t,maxp,w,api,bpi,asi,bsi:longint; 9 10 function max(x,y:longint):longint; 11 begin 12 if x>y then exit(x); 13 exit(y); 14 end; 15 16 begin 17 readln(t,maxp,w); 18 for i:=-t to t do 19 for j:=1 to maxp do 20 f[i,j]:=-1000000000; 21 for i:=1 to t do 22 begin 23 readln(api,bpi,asi,bsi); 24 head:=1; 25 tail:=1; 26 f[i]:=f[i-1]; 27 q[1].s:=0; 28 q[1].w:=f[i-w-1,0]; 29 for j:=1 to maxp do 30 begin 31 inc(tail); 32 q[tail].w:=f[i-w-1,j]+j*api; 33 q[tail].s:=j; 34 while (head<tail)and(q[tail-1].w<q[tail].w) do 35 begin 36 q[tail-1]:=q[tail]; 37 dec(tail); 38 end; 39 while (head<=tail)and(q[tail].s<j-asi) do inc(head); 40 f[i,j]:=max(f[i,j],q[head].w-api*j); 41 end; 42 head:=1; 43 tail:=1; 44 q[1].s:=maxp; 45 q[1].w:=f[i-w-1,maxp]+maxp*bpi; 46 for j:=maxp-1 downto 0 do 47 begin 48 inc(tail); 49 q[tail].w:=f[i-w-1,j]+j*bpi; 50 q[tail].s:=j; 51 while (head<=tail)and(q[tail].w<x) do 52 begin 53 q[tail-1]:=q[tail]; 54 dec(tail); 55 end; 56 while (head<=tail)and(q[head].s>j+bsi) do inc(head); 57 f[i,j]:=max(f[i,j],q[head].w-j*bpi); 58 end; 59 end; 60 writeln(f[t,0]); 61 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……
