Chapter 13.2, Problem 6SC

Program Plan Intro

Recursive helper method:

• The recursive helper method is used to identify how far the recursion has already proceeded or how far it still has to proceed.
• A task may often be solved by handing it over to a recursive helper method.
• The recursive helper method can be defined by slightly changing the original recursive method.

Example for recursive helper method:

• Consider the method “public boolean isPalindrome(int start, int end)” used to check a sentence is palindrome or not. Sometimes this method is inefficient for constructing the new sentences.
• So, a helper method can be introduced to test whether the substrings are palindrome or not. This would be much better than testing the entire sentence is palindrome or not.
• Then the original recursive palindrome method would call the recursive helper method to check the entire sentence is palindrome or not. It is given below,

//recursive palindrome method

public boolean isPalindrome()

{

//calling recursive helper method

return isPalindrome(0, text.length() - 1);

}

• In the above, the method call is not recursive. The “isPalindrome(String)” method calls the helper method “isPalindrome(String, int, int)”.