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What is recursion and what is a base case?

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01

Understand the problem

Explain recursion.

recursion
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Recursion is when a function calls itself on a smaller subproblem until it reaches a base case that stops the recursion. Each call adds a stack frame, so deep recursion risks stack overflow. Many recursive solutions can be rewritten iteratively or memoized.

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04

Read the code

Factorial — recursive
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def factorial(n):
    if n <= 1:          # base case
        return 1
    return n * factorial(n - 1)   # recursive case

print(factorial(4))    # 24
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