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Solution: First Missing Positive

Explore an optimized solution to find the first missing positive integer in an unsorted array using cyclic sort. This lesson helps you understand how to efficiently place numbers in their correct positions, handle constraints, and achieve O(n) time and O(1) space complexity. You will learn to implement the approach and analyze its performance, preparing you to solve similar coding interview problems effectively.

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

  • 231-2^{31} \leq ...