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

def sumDigits(testVariable):
  # Base Case
  if testVariable == "":
    return 0

  # Recursive Case 
  else:
    return int(testVariable[0]) + sumDigits(testVariable[1:])

# Driver Code
print(sumDigits("345"))

# Explanation
The solution to this problem is similar to the solution of finding the length of a string.

For this problem, we remove the first element of the string and call another instance of the same function. The first element of the string is converted to an integer. When the child function returns its value, this converted integer is added to the result.

> The base case remains the same, meaning that the string returns $0$ if is **empty**. 

Let's take a look at the illustration to this problem:

This review provides a detailed analysis of the solution to find the sum of digits in a string


Recursion Fundamentals

Iteration Vs. Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Solution Review: Sum of Digits in a String

Solution: Using Recursion