2483. Minimum Penalty for a Shop - Explanation

class Solution:
    def bestClosingTime(self, customers: str) -> int:
        n = len(customers)
        res = n
        minPenalty = n

        for i in range(n + 1):
            penalty = 0
            for j in range(i):
                if customers[j] == 'N':
                    penalty += 1
            for j in range(i, n):
                if customers[j] == 'Y':
                    penalty += 1

            if penalty < minPenalty:
                minPenalty = penalty
                res = i

        return res

class Solution:
    def bestClosingTime(self, customers: str) -> int:
        n = len(customers)
        cnt = 0

        prefixN = []
        for c in customers:
            prefixN.append(cnt)
            if c == 'N':
                cnt += 1
        prefixN.append(cnt)

        suffixY = [0] * (n + 1)
        for i in range(n - 1, -1, -1):
            suffixY[i] = suffixY[i + 1]
            if customers[i] == 'Y':
                suffixY[i] += 1

        res = n
        minPenalty = n
        for i in range(n + 1):
            penalty = prefixN[i] + suffixY[i]
            if penalty < minPenalty:
                minPenalty = penalty
                res = i

        return res

class Solution:
    def bestClosingTime(self, customers: str) -> int:
        cntY = sum(c == "Y" for c in customers)

        minPenalty = cntY
        res = cntN = 0
        for i, c in enumerate(customers):
            if c == "Y":
                cntY -= 1
            else:
                cntN += 1

            penalty = cntN + cntY
            if penalty < minPenalty:
                res = i + 1
                minPenalty = penalty

        return res

class Solution:
    def bestClosingTime(self, customers: str) -> int:
        res = minPenalty = 0
        penalty = 0

        for i, c in enumerate(customers):
            penalty += 1 if c == 'Y' else -1

            if penalty > minPenalty:
                minPenalty = penalty
                res = i + 1

        return res