Learn essential coding patterns to answer problems and prepare for tech companies' interviews.

Ace the JavaScript Coding Interview

This module teaches us the underlying patterns behind common coding interview questions. By learning these essential patterns, we'll be able to unpack and answer any problem the right way—just by assessing the problem statement. This approach was created by FAANG hiring managers to help us prepare for the typical rounds of interviews at major tech companies like Apple, Google, Meta, Microsoft, and Amazon.

By the end of this module, we'll have the skills we need to unlock even the most challenging questions, grok the coding interview, and level up our career with confidence.

Coding Interview Patterns

# Statement

Given an integer array, `nums`, of length $n$, where all the integers of `nums` are in the range $[1, n]$ and each integer appears once or twice, return an array of all the integers that appear twice.

> **Note:** Write an algorithm that runs in $O(n)$ time and uses only constant auxiliary space, excluding the space occupied by the output.

**Constraints:**

* $n =$ `nums.length`

* $1 \leq n \leq 10^3$

* $1 \leq$ `nums[i]` $\leq n$

* Each element in `nums` appears once or twice.

# Examples

Try to solve the Find All Duplicates in an Array problem.