Marc Lester Tan

The idea to solve this problem is to sort the input array and then use a sliding window approach to find the minimum absolute difference between two consecutive elements. If we find a new low, then clear the result and add the current elements. Add more elements if the current diff is equal to the lowest diff so far.

class Solution {
    fun minimumAbsDifference(arr: IntArray): List<List<Int>> {
        val sorted = arr.sorted()
        var low = 0
        var high = 1
        var lowestDiff = Integer.MAX_VALUE
        var output = ArrayList<List<Int>>()
        
        while(high < sorted.size){
            val diff = Math.abs(sorted[high] - sorted[low])
            
            if(diff < lowestDiff){
                lowestDiff = diff
                output.clear()
            }
            
            if(diff == lowestDiff) output.add(listOf(sorted[low], sorted[high]))
            
            low++
            high++
        }
        
        return output
        
    }
}

Runtime: 496 ms, faster than 30.77% of Kotlin online submissions for Minimum Absolute Difference.
Memory Usage: 50.9 MB, less than 100.00% of Kotlin online submissions for Minimum Absolute Difference.