2714. Left and Right Sum Differences

Easy
Array
Prefix Sum

Description

You are given a 0-indexed integer array nums of size n.

Define two arrays leftSum and rightSum where:

  • leftSum[i] is the sum of elements to the left of the index i in the array nums. If there is no such element, leftSum[i] = 0.
  • rightSum[i] is the sum of elements to the right of the index i in the array nums. If there is no such element, rightSum[i] = 0.

Return an integer array answer of size n where answer[i] = |leftSum[i] - rightSum[i]|.

 

Example 1:

Input: nums = [10,4,8,3]
Output: [15,1,11,22]
Explanation: The array leftSum is [0,10,14,22] and the array rightSum is [15,11,3,0].
The array answer is [|0 - 15|,|10 - 11|,|14 - 3|,|22 - 0|] = [15,1,11,22].

Example 2:

Input: nums = [1]
Output: [0]
Explanation: The array leftSum is [0] and the array rightSum is [0].
The array answer is [|0 - 0|] = [0].

 

Constraints:

  • 1 <= nums.length <= 1000
  • 1 <= nums[i] <= 105

Hints

Hint 1
For each index i, maintain two variables leftSum and rightSum.
Hint 2
Iterate on the range j: [0 … i - 1] and add nums[j] to the leftSum and similarly iterate on the range j: [i + 1 … nums.length - 1] and add nums[j] to the rightSum.

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