The ultimate guide to recursion interviews with strategies developed by FAANG engineers. Practice with real-world interview questions, detailed explanations, and visualizations to prep faster.

If you’ve got an interview coming up and want to brush up on your knowledge, or if you’ve ever struggled with solving coding problems using recursion, you'll find this course helpful.
 
You’ll start with the basics of what recursion is and why it’s important before diving into what it looks like in practice. You’ll see how recursion can help you solve a variety of different math, string, and data structure problems by using interactive code playgrounds that you can execute directly in your browser. You’ll have access to detailed explanations and visualizations for each problem to help you along the way.  
 
By the time you’re done, you’ll be able to use what you’ve learned to solve complex real-world problems and even advance more easily through your interviews at top tech companies.

Recursion for Coding Interviews in Java

# What is a prime number?
A **prime number** is a number greater than 1 that has only two divisors: 1 and the number itself. The first few prime numbers are:

 $2, 3, 5, 7, 11, 13, 17, 19, 23, 29, .....$ 

**Composite** numbers are numbers that are not prime; that is, they have divisors other than $1$ and itself

$4, 6, 8, 9, 10, 12, 14, 15, 16, 18.......$

>The numbers $1$ and $0$ are neither prime nor composite. 

All the numbers are either prime or composite, except for $0$ and $1$.

# Problem Statement
Write a recursive method, named `isPrime()` that checks if a number is prime or not.

## Instructions
1. The method should take two integers as input.
2. The method should return Boolean, meaning it will return *true* if the number is prime or return *false* if the number is not prime.
3. The method should be recursive.  

**Sample Input:** 7

**Sample Output:** true

**Sample Input:** 9

**Sample Output:** false

Good luck!



In this lesson, you will implement the code to check if a number is prime using recursion.

Fundamentals of Recursion

Iteration to Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Challenge 2: Check for Prime Number

What is a prime number?