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Problem: First Missing Positive

Explore how to identify the first missing positive integer in an unsorted array efficiently. Understand the cyclic sort method that places each number in its correct position, enabling a linear time and constant space solution. This lesson helps you implement and analyze an optimized array algorithm in JavaScript.

Statement

Given an unsorted integer array nums, find and return the smallest positive integer that is not present in nums.

Your solution must run in O(n)O(n) time and use O(1)O(1) auxiliary space.

Constraints:

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