PYTHON Solution must be recursive You are not allowed to use

PYTHON
Solution must be recursive. You are not allowed to use loops, or use the python \"in\" operator.

Write a function which is passed 3 parameters, all of which are strings. The function returns a copy of the string s with all occurrences of old_c replaced by new_c. You are not allowed to use the built-in python replace method. You may assume that old_c and new_c are both strings of length 1.

def replace(s, old_c, new_c):

>>> replace(\'science\', \'c\' , \'t\')

\'stiente\'

>>> replace(\'python\', \'s\', \'t\')

\'python\'

>>> replace(\'rocker\', \'r\', \'d\')

\'docked\'

Solution

def replace(s, old_c, new_c):
if s == \'\':
return \'\'
if s[0] == old_c:
return new_c + replace(s[1:], old_c, new_c)
return s[0] + replace(s[1:], old_c, new_c)