Functions: Exercises and Solutions
Factorial using recursion
Exercise
When a function calls itself, this is called recursion. Define a factorial function that does not use a for
loop, but uses recursion.
Solution
def factorial(i):
if not i: # 0 is False
return 1
return i * factorial(i - 1)
print('0! == {0}'.format(factorial(0)))
print('1! == {0}'.format(factorial(1)))
print('2! == {0}'.format(factorial(2)))
print('3! == {0}'.format(factorial(3)))
Output:
0! == 1
1! == 1
2! == 2
3! == 6
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