Make Array Elements Equal to Zero

Description

You are given an integer array nums.

Choose a starting position curr where nums[curr] == 0 and pick a direction: left or right.

Then repeat:

- If curr is outside [0, n - 1], stop.

- If nums[curr] == 0, step in the current direction (increment curr if moving right, decrement if moving left).

- If nums[curr] > 0:

- Decrement nums[curr] by 1.

- Reverse your direction.

- Step in the new direction.

A (starting position, direction) pair is valid if every element of nums becomes 0 by the end of the process.

Return the number of valid selections.

Code

class Solution:
    def countValidSelections(self, nums: List[int]) -> int: