for clarity image https://drive.google.com/open?id=1f0JTn8EpIfpCw4NxpTKMhE6EwZVapQQO
(after analyzing the image with small sample )
there are 0-1023 elements ===> 1024 elements
when root is at height =1, then 1024 elements = ⌊ log 1024 ⌋ + 1 = 10 + 1 = 11 levels.
our main concern is on 512.
0,1,2,3 ...... 512, ....... 1022,1023
There are five hundred and twelve elements before 512 and five hundred eleven elements after it
is my 512 at level-11 ?
yes, due to there are atleast 10 elements less than it ! ===> yes it can be at level-11.
is my 512 at level-2 ?
if my 512 element is at level-2, then there should be atleast (29-1) - 1 i.e., 510 elements grater than 512.
in our range there are 511 elements grater than 512 ===> yes it can be at level-2.
∴ required answer = 11-2=9