Implement the recursive function isPal(), which determines whether a string str is a simple palindrome. A simple palindrome is a string consisting entirely of the characters a-z that reads the same forward and backward. For instance, the upcoming are palindromes:
dad, level, mom, madamimadam, .
Use the following declaration of isPal(): bool isPal (const string& str, int startIndex, int endIndex); It returns true when the substring in the index range [startIndex, endIndex) is a palindrome.
The conditions are Stopping Condition:
Result is true when startIndex >= endIndex -1 Result is false when str[startIndex] != str[endIndex-1]
Recursive Step:
Determine whether the substring of the str in the index range [startIndex+1, endIndex-1] is a palindrome.