Alex Martinez

May 9, 20232 min

DataWeave programming challenge #6: Using tail-recursion to get the factorial of a number

Updated: Aug 31, 2023

Other posts from this series:

  1. DataWeave programming challenge #1: Add numbers separated by paragraphs and get the max number

  2. DataWeave programming challenge #2: Rock Paper Scissors game score system

  3. DataWeave programming challenge #3: Count palindrome phrases using the Strings module

  4. DataWeave programming challenge #4: Solve the Tower of Hanoi mathematical puzzle

  5. DataWeave programming challenge #5: Reverse a phrase's words, but keep the punctuation

  6. DataWeave programming challenge #6: Using tail-recursion to get the factorial of a number

  7. DataWeave programming challenge #7: Modify certain values from a JSON structure

  8. DataWeave programming challenge #8: Sum all digits to get a 1-digit number

In this post:

  • Input

  • Explanation of the problem

  • Expected output

  • Clues

  • Answer

Try to solve this challenge on your own to maximize learning. We recommend you refer to the DataWeave documentation only. Try to avoid using Google or asking others so you can learn on your own and become a DataWeave expert!

Input

Consider the following input payload (can be of txt format):

3
 5
 -6
 300

Explanation of the problem

  1. Create a tail-recursive function to get the factorial of each positive number from the payload.

  2. Sum the results.

  3. Retrieve the digits/characters located at positions 20-25.

  4. Make sure to return a number and not a string.

  5. Numbers 0 or less won't be calculated.

For example:

  • The factorial of 3 is 6 (3 x 2 x 1)

  • The factorial of 5 is 120 (5 x 4 x 3 x 2 x 1)

  • The factorial of -6 won't be calculated so the result will be 0

  • And so on

  • Once the results are summed (6 + 120 + 0...), extract the digits at indexes 20 to 25.

  • Return this last 6-digit number.

Expected output

In this case, the expected output would be:

537046

Clues

If you're stuck with your solution, feel free to check out some of these clues to give you ideas on how to solve it!

Answer

If you haven't solved this challenge yet, we encourage you to keep trying! It's ok if it's taking longer than you thought. We all have to start somewhere ✨ Check out the clues and read the docs before giving up. You got this!! 💙

There are many ways to solve this challenge, but you can find here one of my solutions!

Feel free to comment your code below for others to see! 😄

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