Question

How to find the length of the longest consecutive sequence of an unsorted array of integers in Kotlin

Answer 1

fun longestConsecutive(nums: IntArray): Int {
    val numSet = nums.toHashSet()
    var longestStreak = 0

    for (num in numSet) {
        // Only start counting if it's the beginning of a sequence
        if (!numSet.contains(num - 1)) {
            var currentNum = num
            var currentStreak = 1

            while (numSet.contains(currentNum + 1)) {
                currentNum++
                currentStreak++
            }

            longestStreak = maxOf(longestStreak, currentStreak)
        }
    }

    return longestStreak
}


fun main() {
    val nums = intArrayOf(680, 4, 590, 3, 2, 1)
    
    println("Longest consecutive sequence length: ${longestConsecutive(nums)}")
}

 
  
/*
run:

Longest consecutive sequence length: 4

*/

 

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