0-puts_recursion.c void _puts_recursion(char *s); 1-print_rev_recursion.c void _print_rev_recursion(char *s); 2-strlen_recursion.c int _strlen_recursion(char *s); 3-factorial.c int factorial(int n); 4-pow_recursion.c int _pow_recursion(int x, int y); 5-sqrt_recursion.c int _sqrt_recursion(int n); 6-is_prime_number.c int is_prime_number(int n); 7-is_palindrome.c int is_palindrome(char *s); 100-wildcmp.c int wildcmp(char *s1, char *s2);