The ultimate recursion guide! Master basics, solve real-world problems, and get interview-ready in hours with FAANG engineers’ proven strategies.

If you’ve ever struggled with solving coding problems using recursion, or if you need to brush up your recursion skills for an interview, this course is for you! We will start with the basics of recursion before we practice solving actual coding problems. You’ll have access to detailed explanations and visualizations for each problem to help you along the way.

By the time you have completed this course, you’ll be able to use all the concepts of recursion to solve complex, real-world problems. We hope that this course will help you ace all the recursion related questions during interviews at top tech companies!

Recursion for Coding Interviews in Python

import node

class LinkedList: 
	def __init__(self) :
		self.head = None

	def append(self, new_data): 
		new_node = node.Node(new_data) 
		
		if self.head is None : # If head node is null 
			self.head = new_node 
			return

		last = self.head 
		while (last.next): 
			last = last.next
		last.next =  new_node # add new node to end of list

	def printList(self):
		temp = self.head
		while(temp):
			print(temp.data)
			temp = temp.next

class Node: 
	def __init__(self, data): 
		self.data = data 
		self.next = None


 import linkedList as l

def length(testVariable, head) :
	# Base case
	if (not head) :
		return 0
		
	# Recursive case
	else :
		return 1 + length(testVariable, head.next) 

# Driver Code
myLinkedList = l.LinkedList() 
myLinkedList.append(3) 
myLinkedList.append(4) 
myLinkedList.append(7) 
myLinkedList.append(11) 

print(length(myLinkedList, myLinkedList.head))

## Explanation

The **base case** for this problem is when a linked list contains **no nodes**. In this case, we return $0$ as the length of that linked list.

For the **recursive case**, we move the head pointer to its next node, `head.next`, and call another instance of the same function recursively. When this child function returns, we add $1$ to the result.

Our solution is based on the following premise:
$length \: of \: a \: linked \: list = 1 + length \: of \: a \: linked \: list \: with \: head \:pointer \: moved \:one \: step\: ahead$.

Let's dry-run our code:


This review provides a detailed analysis of the solution to find the length of a linked list.


Recursion Fundamentals

Iteration Vs. Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Solution Review: Length of a Linked List

Solution: Using Recursion

Explanation