Objective : Write an algorithm to find Whether Given String is palindrome or Not.
Input: A String,
Output: true or false on whether string is palindrome or not
Approach:
- Use recursive approach
- Compare first and last characters if they are not same- return false
- If they are same make, remove the first and last characters and make a recursive call.
Example:
Jain niaJ => compare ‘J’ with ‘J’ =>returns true ain nia => compare ‘a’ with ‘a’ =>returns true in ni => compare ‘i’ with ‘i’ =>returns true n n => compare ‘n’ with ‘n’ =>returns true string length <2 => returns true
Complete Code:
| //Use recursive approach | |
| //Compare first and last characters if they are not same- return false | |
| //If they are same make, remove the first and last characters and make a recursive call. | |
| public class Palindrome { | |
| public Boolean isPalindrome(String strX) { | |
| if (strX.length() < 2) | |
| return true; | |
| if (strX.charAt(0) == strX.charAt(strX.length() – 1)) { | |
| return isPalindrome(strX.substring(1, strX.length() – 1)); | |
| } else | |
| return false; | |
| } | |
| public static void main(String args[]) { | |
| String S1 = "Sumit"; | |
| String S2 = "SumuS"; | |
| String S3 = "ABCDEFGHGFEDCBA"; | |
| String S4 = "Jain niaJ"; | |
| String S5 = "JasasddfwfcsJ"; | |
| Palindrome p = new Palindrome(); | |
| System.out.println("Is " + S1 + " Palindrome ??? :" | |
| + p.isPalindrome(S1)); | |
| System.out.println("Is " + S2 + " Palindrome ??? :" | |
| + p.isPalindrome(S2)); | |
| System.out.println("Is " + S3 + " Palindrome ??? :" | |
| + p.isPalindrome(S3)); | |
| System.out.println("Is " + S4 + " Palindrome ??? :" | |
| + p.isPalindrome(S4)); | |
| System.out.println("Is " + S5 + " Palindrome ??? :" | |
| + p.isPalindrome(S5)); | |
| } | |
| } |
Output:
Is Sumit Palindrome ??? :false Is SumuS Palindrome ??? :true Is ABCDEFGHGFEDCBA Palindrome ??? :true Is Jain niaJ Palindrome ??? :true Is SumuaS Palindrome ??? :false
This program is wrong. Try modifying the second string to SumuaS and check. You will get the wrong result.
Thanks for pointing it out…I have corrected it.
What if the String contains capital letters and small letters in between? Example Nitin . It should return true right?