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# PROGRAMMING CHALLENGES

# Recursive Greatest Common Divisor

### Difficulty:

3 Hard

2.5 Recursion

### Topic:

The following pseudocode calculates the greatest common divisor (GCD) of two numbers using recursion. Rewrite this algorithm to use iteration instead.

The GCD can be calculated using the Euclidean algorithm. Consider how a while loop can replace the recursive calls to continuously apply the GCD calculation.

FUNCTION gcd(a, b) IF b == 0 RETURN a ELSE RETURN gcd(b, a % b) ENDFUNCTION

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