Challenge: Smallest Positive Missing Number

Let’s find the smallest positive missing number in this challenge.


Given an unsorted array, find the smallest positive number missing in the array. Consider 1 as the smallest positive number.


An integer array.


A missing integer. Otherwise -1 if not found.

Sample input

array = { 8, 5, 6, 1, 9, 11, 2, 7, 4, 10 }

Sample output

missing number = 3

Let’s check the illustration below to better understand the question.

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