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01. Define a function that adds two numbersE02. Write a function that returns a greetingE03. Implement a function to find the maximum of threeE04. Create a function to join words with a separatorE05. Write a function that returns the length of a sequenceE06. Implement a function with a default argumentE07. Create a function that accepts any number of argsE08. Write a function that handles keyword argumentsE09. Implement a function that returns multiple valuesE10. Write a function that modifies a passed listE11. Define a function that reads a global variableE12. Write a function with a simple docstringE13. Write a function that demonstrates nonlocal usageM14. Create a function factory returning customized functionsM15. Implement argument unpacking with *args and **kwargsM16. Write a function that avoids mutable default argsM17. Create a function with keyword-only parametersM18. Implement a simple recursive function with a base caseM19. Implement a decorator that logs function callsH20. Write a decorator that memoizes function resultsH

Problem No 18

Implement a simple recursive function with a base case

Medium

≈ 17 minute session

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Summary

Implement recursion with a clear base case by writing a factorial function.

Problem statement

Implement factorial(n) that returns n! (n factorial) for non-negative integers using recursion. The base case is n == 0 which returns 1. Validate input: n must be an integer and non-negative; raise TypeError for non-integers and ValueError for negative integers. Use recursion for the general case.

Task

Write a recursive factorial(n) function that handles base cases and validates input.

Examples

Factorial of 4

Input

factorial(4)

Output

24

Explanation

4! = 4 * 3 * 2 * 1 = 24; recursion reduces n until base case 0.

Input format

A single integer n passed to factorial(n).

Output format

Return an integer equal to n!. The returned value will be converted to a string for comparison.

Constraints

Use recursion with a base case n == 0. Validate that n is a non-negative integer.

Samples

Sample input 0

factorial(5)

Sample output 0

120

Explanation 0

5! = 120

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