Two Pointer: main idea- loop through each seat and check if there is a person. record previous occupied seat index after move to next position. find the max distance between current seat with pp and previous seat with people. (cur - prev ) // 2 will be idea seat. keep this procedure and update the current best result to res.

there are two special cases need to consider where seat at either two ends is empty. so we discuss if beginning prev is None and if seat[-1] == 0 cases, where we compare res and i - prev instead of (i-prev)//2.

class Solution:
# time O(N) space O(1)
    def maxDistToClosest(self, seats: List[int]) -> int:
        # step1: initialize res and prev
        res = float('-inf')
        prev = None
        # step2: loop through seats
        for i in range(len(seats)):
            # step3 check if current seat is occupied 
            if seats[i] == 1:
                # step3.1: check if prev seat is recorded(if begining position be a good candidate to sit )
                if prev == None:
                    res = i
                # step3.2 if prev has record, compare res and (i-prev)//2 and update best pos to res
                else:
                    res = max(res,(i-prev)//2)
                # step 3.3: update prev with current seat  before entering next seat
                prev = i
        # step4 after loop end: check if last seat occupied, if not, compare best res for far with potential sit at end distance 
        if seats[-1] != 1:
            res = max(res,len(seats)-1-prev)
        # step5 
        return res