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Solution: First Missing Positive

Explore how to efficiently find the smallest missing positive integer in an unsorted array using a cyclic sort approach. Learn to implement an O(n) time and constant space algorithm by placing numbers in their correct positions and identifying the first mismatch.

Statement

Given an unsorted integer array, nums, return the smallest missing positive integer. Create an algorithm that runs with an O(n)O(n) time complexity and utilizes a constant amount of space.

Note: The smallest missing positive isn’t the first positive number that’s missing in the range of elements in the input, but the first positive number that’s missing if we start from 11.

Constraints:

  • 11 \leq nums.length 105\leq 10^5 ...