Watch 10 video solutions for Ways to Make a Fair Array, a medium level problem involving Array, Prefix Sum. This walkthrough by NeetCode has 747,485 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
You are given an integer array nums. You can choose exactly one index (0-indexed) and remove the element. Notice that the index of the elements may change after the removal.
For example, if nums = [6,1,7,4,1]:
1 results in nums = [6,7,4,1].2 results in nums = [6,1,4,1].4 results in nums = [6,1,7,4].An array is fair if the sum of the odd-indexed values equals the sum of the even-indexed values.
Return the number of indices that you could choose such that after the removal, nums is fair.
Example 1:
Input: nums = [2,1,6,4] Output: 1 Explanation: Remove index 0: [1,6,4] -> Even sum: 1 + 4 = 5. Odd sum: 6. Not fair. Remove index 1: [2,6,4] -> Even sum: 2 + 4 = 6. Odd sum: 6. Fair. Remove index 2: [2,1,4] -> Even sum: 2 + 4 = 6. Odd sum: 1. Not fair. Remove index 3: [2,1,6] -> Even sum: 2 + 6 = 8. Odd sum: 1. Not fair. There is 1 index that you can remove to make nums fair.
Example 2:
Input: nums = [1,1,1] Output: 3 Explanation: You can remove any index and the remaining array is fair.
Example 3:
Input: nums = [1,2,3] Output: 0 Explanation: You cannot make a fair array after removing any index.
Constraints:
1 <= nums.length <= 1051 <= nums[i] <= 104