LeetCode in Kotlin

1685. Sum of Absolute Differences in a Sorted Array

Medium

You are given an integer array nums sorted in non-decreasing order.

Build and return an integer array result with the same length as nums such that result[i] is equal to the summation of absolute differences between nums[i] and all the other elements in the array.

In other words, result[i] is equal to sum(|nums[i]-nums[j]|) where 0 <= j < nums.length and j != i (0-indexed).

Example 1:

Input: nums = [2,3,5]

Output: [4,3,5]

Explanation: Assuming the arrays are 0-indexed, then

result[0] = |2-2| + |2-3| + |2-5| = 0 + 1 + 3 = 4,

result[1] = |3-2| + |3-3| + |3-5| = 1 + 0 + 2 = 3,

result[2] = |5-2| + |5-3| + |5-5| = 3 + 2 + 0 = 5.

Example 2:

Input: nums = [1,4,6,8,10]

Output: [24,15,13,15,21]

Constraints:

• 2 <= nums.length <= 105
• 1 <= nums[i] <= nums[i + 1] <= 104

Solution

class Solution {
    fun getSumAbsoluteDifferences(nums: IntArray): IntArray {
        val len = nums.size
        val preSums = IntArray(len)
        for (i in 1 until len) {
            preSums[i] = preSums[i - 1] + nums[i - 1]
        }
        val postSums = IntArray(len)
        for (i in len - 2 downTo 0) {
            postSums[i] = postSums[i + 1] + nums[i + 1]
        }
        val result = IntArray(len)
        for (i in 0 until len) {
            result[i] = nums[i] * i - preSums[i] + postSums[i] - nums[i] * (len - i - 1)
        }
        return result
    }
}

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