Need help to optimize my code

Question

https://code.sololearn.com/cuaeNp2cIEtB/?ref=app
I got AC when time limit is 0.4 s
But then the time limit become 0.28 s and i got TLE
Can anyone help me, pls?

The goal is to find biggest xor of two number, but the number must be biggest and second biggest in a range.
For example:

8 15 20 23 1 10 9

The output must be
29 (23 xor 10)

Why not 31 (8 xor 23)?
Because in range of 8 to 23, the 2 biggest number is 20 & 23, so we can only xor 20 with 23, not 8 and 23.

The program is implementation of monotonic stack (next greater element)

Answer 1

Coder Kitten , sorry i copy-paste the code without delete the comment.

Answer 2

Coder Kitten
Because if we look at the index, 8 is at index 0, and 23 is at index 3

From index 0 and 3 if i write in descending order, it would be

23
20
15
8

So, 8 xor 23 is not valid because 8 neither biggest from range (0-3) nor second biggest. But when we look at 3rd index to 5th, in descending order:

23
10
1

So if we do xor (23 and 10) is valid (both is biggest and second biggest in range (3 to 5)).

Sorry for my bad English.