P3401: [Usaco2009 Mar]Look Up 仰望

这道题第一眼还以为是树状数组，于是乎打着打着也是能过的

 const maxn=;
 var n,i,j,maxx:longint;
 h,l:array[..] of longint;
 p:array[..] of longint;
 function lowbit(x:longint):longint;
 begin
   exit(x and (-x));
 end;
 procedure insert(x,i:longint);
 var tem:longint;
 begin
   tem:=x;
   while tem<=maxx+ do
     begin
       p[tem]:=i;
       tem:=tem+lowbit(tem);
     end;
 end;
 function work(x:longint):longint;
 var tem:longint;
 begin
   tem:=maxn;
   while x> do
     begin
       if (p[x]<tem) and (p[x]<>) then tem:=p[x];
       x:=x-lowbit(x);
     end;
   if tem=maxn then exit()
     else exit(tem);
 end;
 begin
   readln(n);
   for i:= to n do
     begin
       readln(h[i]);
       if h[i]>maxx then maxx:=h[i];
     end;
   for i:= to n do
     h[i]:=maxx+-h[i];
   l[n]:=;
   insert(h[n],n);
   for i:=n- downto  do
     begin
       l[i]:=work(h[i]-);
       insert(h[i],i);
     end;
   for i:= to n- do
     writeln(l[i]);
   write(l[n]);
 end.

然而这道题正确解法是 单调栈！！

 type
   node=record
     num,h:longint;
   end;
 var n,i,j,num,now:longint;
 stack:array[..] of node;
 h,l:array[..] of longint;
 begin
   readln(n);
   for i:= to n do
     readln(h[i]);
   now:=;
   for i:=n downto  do
     begin
       while (now>) and (stack[now].h<=h[i]) do
         dec(now);
       l[i]:=stack[now].num;
       inc(now);
       stack[now].h:=h[i];
       stack[now].num:=i;
     end;
   for i:= to n do writeln(l[i]);
 end.

好吧，差不多，差不多=-=//

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