划分树

至此，我的划分树模版终于完成

const maxn=100000+10;
var s,t:array[0..20,0..maxn] of longint;
    a,b,rk:array[0..maxn] of longint;
    i,j,n,m,x,y,k:longint;
procedure sort(l,r:longint);
 var i,j,m,temp:longint;
 begin
 i:=l;j:=r;x:=a[(i+j)>>1];
 repeat
  while b[a[i]]<b[x] do inc(i);
  while b[a[j]]>b[x] do dec(j);
  if i<=j then
   begin
   y:=a[i];a[i]:=a[j];a[j]:=y;
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
procedure init;
 begin
 readln(n,m);
 for i:=1 to n do read(b[i]);
 for i:=1 to n do a[i]:=i;
 sort(1,n);
 end;
procedure build(h,l,r:longint);
 var i,p,mid:longint;
 begin
 mid:=(l+r)>>1;p:=0;
 for i:=l to r do
  if t[h,i]<=mid then
   begin
    t[h+1,l+p]:=t[h,i];
    inc(p);
    s[h,i]:=p;
   end
  else
   begin
    t[h+1,mid+1+i-p-l]:=t[h,i];
    s[h,i]:=p;
   end;
 if l=r then exit;
 build(h+1,l,mid);
 build(h+1,mid+1,r);
 end;
function find(h,l,r,x,y,k:longint):longint;
 var ll,rr,mid:longint;
 begin
 if l=r then exit(t[h,l]);
 mid:=(l+r)>>1;
 if l=x then ll:=0 else ll:=s[h,x-1];rr:=s[h,y]-ll;
 if rr>=k then exit(find(h+1,l,mid,l+ll,l+rr+ll-1,k))
 else exit(find(h+1,mid+1,r,mid+1+x-l-ll,mid+1+y-l-rr-ll,k-rr));
 end;
procedure main;
 begin
 for i:=1 to n do t[0,a[i]]:=i;
 build(0,1,n);
 for i:=1 to m do
  begin
  readln(x,y,k);
  writeln(b[a[find(0,1,n,x,y,k)]]);
  end;
 end;
begin
 assign(input,'input.txt');assign(output,'output.txt');
 reset(input);rewrite(output);
 init;
 main;
 close(input);close(output);
end.

其中有一个技巧是从盾哥那里学来的，就是求sa数组，不用更改原数组，而是b[a[i]]成为一个有序数组即可，对sort稍作修改就可以

这估计是c++党没有的福利吧（偷笑……）

ps：貌似这个版本可以支持的操作不多，不如HDU3473求中位数，不过貌似可以开一个结构体，记录下它的原值然后乱搞也行？

但还是把两个版本的都记一下吧

var  s,t:array[0..20,0..200000] of longint;
     a,rk:array[0..200000] of longint;
     i,n,m,x,y,k,j:longint;
 procedure sort(l,r:longint);
 var i,j,m,temp:longint;
 begin
 i:=l;j:=r;m:=a[(i+j)>>1];
 repeat
  while a[i]<m do inc(i);
  while a[j]>m do dec(j);
  if i<=j then
   begin
   temp:=a[i];a[i]:=a[j];a[j]:=temp;
   inc(i);dec(j);
   end;
 until i>j;
 if i<r then sort(i,r);
 if j>l then sort(l,j);
 end;
  procedure init;
   begin
     readln(n,m);
     for i:=1 to n do read(a[i]);t[0]:=a;
     sort(1,n);
   end;
 procedure build(h,l,r:longint);
  var  mid,i,lp,rp,lm:longint;
  begin
  mid:=(l+r)>>1;lm:=mid-l+1;lp:=l;rp:=mid+1;
  for i:=l to mid do
   if a[i]<a[mid] then dec(lm);
  for i:=l to r do
   begin
   if i=l then s[h,i]:=0 else s[h,i]:=s[h,i-1];
   if t[h,i]=a[mid] then
    begin
    if lm<>0 then
     begin
     dec(lm);inc(s[h,i]);t[h+1,lp]:=t[h,i];inc(lp);
     end
    else begin t[h+1,rp]:=t[h,i];inc(rp);end;
    end
   else
    if t[h,i]<a[mid] then begin inc(s[h,i]);t[h+1,lp]:=t[h,i];inc(lp);end
   else begin t[h+1,rp]:=t[h,i];inc(rp);end;
   end;
  if l=r then exit;
  build(h+1,l,mid);
  build(h+1,mid+1,r);
  end;
 function find(h,l,r,x,y,k:longint):longint;
  var mid,ll,rr:longint;
  begin
  if l=r then exit(t[h,l]);
  mid:=(l+r)>>1;
  if l=x then ll:=0 else ll:=s[h,x-1];rr:=s[h,y]-ll;
  if rr>=k then exit(find(h+1,l,mid,l+ll,l+ll+rr-1,k))
  else exit(find(h+1,mid+1,r,mid+1+x-l-ll,mid+1+y-l-ll-rr,k-rr));
  end;
 procedure main;
  begin
   build(0,1,n);
   for i:=1 to m do
    begin
     readln(x,y,k);
     writeln(find(0,1,n,x,y,k));
    end;
  end;
begin
  init;
  main;
end.