I’m sticking to the same variables in the editorial in the below link
How are we removing a from the stack when br >=ar (even if br is not yet finalized)?
What if br might now be >=ar, but after I process elements before a in the stack, then the current br will become less than the removed a, which implies that I shouldn’t have popped a from the stack?
I know that this case is not going to happen because the code is working, but I don’t know why.
I thought about it for a while, and I noticed that if b is going to be restricted by an element that is before a and not by a, then br will still always be bigger than ar because if b will first touch the element that is before a and not a, then it must touch from a point that is higher than balloon a.
I noticed this by some drawings, but it’s not very convincing.
Is this reasoning correct and enough?
a better reasoning would be appreciated