Question

How to get the first missing smallest positive integer in an unsorted integer list with Kotlin

Answer 1

fun findSmallestMissingNumber(arr: List<Int>): Int {
    val numSet = arr.toSet() // Convert list to a set for fast lookup

    for (index in 1..arr.maxOrNull()!! + 1) {
        if (!numSet.contains(index)) {
            return index
        }
    }

    return -1 // If no missing number is found
}

fun main() {
    val arr = listOf(3, 4, -1, 1)
    
    println(findSmallestMissingNumber(arr))
}

 
  
/*
run:
  
2

*/

 

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