Minimum Number of Operations to Move All Balls to Each Box LeetCode solution in Python

1
# Runtime: 68 ms (Top 97.39%) | Memory: 14.2 MB (Top 53.70%)
2
class Solution:
3
    def minOperations(self, boxes: str) -> List[int]:
4
        ans = [0] * len(boxes)
5
        leftCount, leftCost, rightCount, rightCost, n = 0, 0, 0, 0, len(boxes)
6
        for i in range(1, n):
7
            if boxes[i - 1] == "1":
8
                leftCount += 1
9
            leftCost += leftCount  # each step move to right, the cost increases by # of 1s on the left
10
            ans[i] = leftCost
11
        for i in range(n - 2, -1, -1):
12
            if boxes[i + 1] == "1":
13
                rightCount += 1
14
            rightCost += rightCount
15
            ans[i] += rightCost
16
        return ans