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

# Problem Statement
Implement a function that takes an array `arr`, a `testVariable` (containing the number to search) and `currentIndex` (containing the starting index) as parameters. This function should output the index of the first occurrence of `testVariable` in `arr`. If `testVariable` is not found in `arr` it should return $-1$.

> Try to implement your solution recursively.

## Input
1. A variable `arr` that contains the array that will be searched.
2. A variable `testVariable`, being the number that will be searched.
3. A variable `currentIndex` that contains the starting index of the `arr` array.

## Output
Index of the first occurrence of `testVariable` in `arr`

## Sample Input
```
arr = [9, 8, 1, 8, 1, 7]
targetNumber = 1
currentIndex = 0
```

## Sample Output
```
2
```

## Try it Yourself!
Try this challenge yourself before examining the solution. Goodluck!

Given an array, find the first occurrence of the target number.

Recursion Fundamentals

Iteration Vs. Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Challenge 2: Search First Occurrence of a Number

Problem Statement