BZOJ1669: [Usaco2006 Oct]Hungry Cows饥饿的奶牛

 1 var a,sta:array[0..5010] of longint;
 2     i,top,n,j:longint;
 3 function search(x:longint):longint;
 4  var l,r,mid:longint;
 5  begin
 6  l:=1;r:=top;
 7  while l<>r do
 8   begin
 9   mid:=(l+r) div 2;
10   if sta[mid]>x then r:=mid else l:=mid+1;
11   end;
12  exit(l);
13  end;
14 function lis:longint;
15   begin
16   top:=1;sta[1]:=a[1];
17   for i:=2 to n do
18    begin
19    if a[i]<sta[1] then j:=1
20    else if a[i]>=sta[top] then j:=top+1
21    else j:=search(a[i]);
22    if j>top then begin inc(top);sta[top]:=a[i];end;
23    if a[i]<sta[j] then sta[j]:=a[i];
24    end;
25   exit(top);
26  end;
27 begin
28   assign(input,‘input.txt‘);assign(output,‘output.txt‘);
29   reset(input);rewrite(output);
30   readln(n);
31   for i:=1 to n do read(a[i]);
32   writeln(lis);
33   close(input);close(output);
34 end.