# Calculating the factorial of a number # is a good way to practice recursion. Below # are examples of both recursive and iterative # approaches to calculating a factorial. Of course # python has its own builtin math module that # can also take care of factorials. import math # A recursive function to calculate the # factorial of N def recursiveFactorial(n): if n == 1: return n return n * recursiveFactorial(n - 1) # Iterative calculation of the factorial # of N def iterativeFactorial(n): result = 1 while n > 1: result *= n n = n-1 return result # Builtin python math.factorial of N def pythonLib(n): return math.factorial(n) print("Iterative factorial of 5: ", iterativeFactorial(5)) print("Recursive factorial of 5: ", recursiveFactorial(5)) print("math.factorial of 5: ", pythonLib(5)) print("Iterative factorial of 10: ", iterativeFactorial(10)) print("Recursive factorial of 10: ", recursiveFactorial(10)) print("math.factorial of 10: ", pythonLib(10)) print("Iterative factorial of 15: ", iterativeFactorial(15)) print("Recursive factorial of 15: ", recursiveFactorial(15)) print("math.factorial of 15: ", pythonLib(15)) # my results: # Iterative factorial of 5: 120 # Recursive factorial of 5: 120 # math.factorial of 5: 120 # Iterative factorial of 10: 3628800 # Recursive factorial of 10: 3628800 # math.factorial of 10: 3628800 # Iterative factorial of 15: 1307674368000 # Recursive factorial of 15: 1307674368000 # math.factorial of 15: 1307674368000
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Thursday, March 3, 2011
Python - Compute the factorial of N with recursion (among others)
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