Leetcode 1783 Solution

This article provides solution to leetcode question 1783 (ways-to-make-a-fair-array)
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https://leetcode.com/problems/ways-to-make-a-fair-array

Solution

class Solution:
    def waysToMakeFair(self, nums: List[int]) -> int:
        total = sum(nums)
        ans = 0

        dp1 = [0] * len(nums)
        for i in range(len(nums)):
            dp1[i] = dp1[i - 1] if i > 0 else 0

            if i % 2 == 0:
                dp1[i] += nums[i]

        dp2 = [0] * len(nums)
        for i in range(len(nums) - 1, -1, -1):
            dp2[i] = dp2[i + 1] if i < len(nums) - 1 else 0

            if i % 2 == 1:
                dp2[i] += nums[i]

        for i in range(len(nums)):
            left_sum = dp1[i - 1] if i > 0 else 0
            right_sum = dp2[i + 1] if i < len(nums) - 1 else 0

            if (left_sum + right_sum) * 2 + nums[i] == total:
                ans += 1

        return ans