2. (Recursion and Recurrence Relations) (a) (10 pts) Write a recursive function

Question

2. (Recursion and Recurrence Relations) (a) (10 pts) Write a recursive function that takes a string of length n and rctums I if the string is a palindrome, 0 if the string is not a palindrome. A palindrome is a string that is spelled the same forwards as it is backwards. E.g., "abba" and "aba" are both palindromes, but "abb" is not. The empty string. , is also a palindrome. For simplicity, you may assume the string passed to your function contains lowercase letters only, and no spaces. Do not call strlen _under any circumstances! The function signature is int is Palindrome (char *str, int n) i

Explanation / Answer

#include <stdio.h>

// Funciton declaration for palindrome function
int palindrome (char *str, int n);

int main ()
{
   int i, len = 0, result;
   char string1[100];

   // User input string
   printf("Enter the string :: ");
   scanf("%s", string1);

   // Finding string length
   for(i = 0; string1[i] != ''; i++) {
   len++;
   }

   // Function call
   result = palindrome(string1, len);

   // Output message
   if (result == 1)
   printf("Entered String is palindrome ");
   else
   printf("Entered String is not a palindrome ");

   return 0;
}

// Function definition for palindrome function
int palindrome (char *str, int n)
{
   int middle, end, begin;
   middle = n/2;
   end = n-1;
   for (begin = 0; begin < middle ; begin++) {
   if (str[begin] != str[end]) {
   return 0; // string is not palindrome
   }
   end--;
   }

   if (begin == middle)
   return 1; // string is palindrome
}

/*************** OUTPUT OF PROGRAM ****************
Enter the string :: abba
Entered String is palindrome

Enter the string :: abc
Entered String is not a palindrome

Enter the string :: aba
Entered String is palindrome
****************************************************/

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