Function to copy string (Iterative and Recursive)

Given two strings, copy one string to another using recursion. We basically need to write our own recursive version of strcpy in C/C++

Examples: 

Input : s1 = "hello"
 s2 = "geeksforgeeks"
Output : s2 = "hello"

Input : s1 = "geeksforgeeks"
 s2 = ""
Output : s2 = "geeksforgeeks"

Iterative: Copy every character from s1 to s2 starting from index = 0 and in each call increase the index by 1 until s1 doesn't reach to end; 

Implementation:

GEEKSFORGEEKS

Time Complexity: O(m), Here m is the length of string s1.
Auxiliary Space: O(1), As constant extra space is used.

Recursive: Copy every character from s1 to s2 starting from index = 0 and in each call increase the index by 1 until s1 doesn't reach to end; 

Implementation:

GEEKSFORGEEKS

Time Complexity: O(m), Here m is the length of string s1.
Auxiliary Space: O(m), due to recursive call stack