Problem: First Missing Positive

Medium

30 min

Understand how to identify and return the smallest missing positive integer from an unsorted array by applying cyclic sort. This lesson helps you develop an efficient O(n) time and constant space solution, enabling you to handle similar array-based problems in coding interviews.

Statement

Given an unsorted integer array, nums, return the smallest missing positive integer. Create an algorithm that runs with an $O(n)$ 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 $1$ .

Constraints:

$1 \leq$ nums.length $\leq 10^5$
$-2^{31} \leq$ nums[i] $\leq 2^{31} - 1$

Problem: First Missing Positive

Medium

30 min

Statement

Given an unsorted integer array, nums, return the smallest missing positive integer. Create an algorithm that runs with an $O(n)$ 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 $1$ .

Constraints:

$1 \leq$ nums.length $\leq 10^5$
$-2^{31} \leq$ nums[i] $\leq 2^{31} - 1$

Problem: First Missing Positive

Statement

Examples

Understand the problem

Figure it out!

Try it yourself

Problem: First Missing Positive

Statement

Examples

Understand the problem

Figure it out!

Try it yourself