The ultimate guide to recursion interviews. Developed by FAANG engineers, practice with real-world C++ problems, interactive code playgrounds, and get interview-ready in just a few hours.

If you’ve ever struggled with solving coding problems using recursion, or if you’ve just got an interview coming up and want to brush up on your knowledge, you’ll definitely 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, using interactive code playgrounds 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 C++

# What is a Fibonacci Sequence?

The Fibonacci sequence is one of the most famous formulas in mathematics. Each number in the sequence is the sum of the two numbers that precede it.

So, the sequence goes:

$ 0, 1, 1, 2, 3, 5, 8, 13, 21, 34 ..... $ 

### Generic Mathematical Notation
Any number, at position n in the series, can be calculated using the following equation:

$F$n $=F$n-2$+F$n-1

By default, the first and second number in the sequence are 0 and 1

$F$1 $= 0$

$F$2 $= 1$

$F$3 $=F$1$+F$2
 $=1 + 0= 1$

$F$4 $=F$2$+F$3
 $=1 + 1= 2$

$F$5 $=F$3$+F$4
 $=1 + 2= 3$

$F$6 $=F$4$+F$5
 $=2 + 3= 5$

$F$7 $=F$5$+F$6
 $=3 + 5= 8$

$F$8 $=F$6$+F$7
 $=5 + 8= 13$


Below is a visualization for the computation of the first eight elements in the Fibonacci sequence:

# What is a Fibonacci Sequence?

The Fibonacci sequence is one of the most famous formulas in mathematics. Each number in the sequence is the sum of the two numbers that precede it.

So, the sequence goes:

$ 0, 1, 1, 2, 3, 5, 8, 13, 21, 34 ..... $ 

## Generic Mathematical Notation
Any number, at position n in the series, can be calculated using the following equation:

$F$n $=F$n-2$+F$n-1

By default, the first and second number in the sequence are 0 and 1

$F$1 $= 0$

$F$2 $= 1$

$F$3 $=F$1$+F$2
 $=1 + 0= 1$

$F$4 $=F$2$+F$3
 $=1 + 1= 2$

$F$5 $=F$3$+F$4
 $=1 + 2= 3$

$F$6 $=F$4$+F$5
 $=2 + 3= 5$

$F$7 $=F$5$+F$6
 $=3 + 5= 8$

$F$8 $=F$6$+F$7
 $=5 + 8= 13$


Below is a visualization for the computation of the first eight elements in the Fibonacci sequence:

In this lesson, we will learn how to compute the Fibonacci sequence using recursion.

Recursion Fundamentals

Recursion with Numbers

Recursion With Strings

Recursion With Arrays

Recursion with Data Structures

Computing Fibonacci Sequence

What is a Fibonacci Sequence?

Generic Mathematical Notation