Question

A palindrome is a word or a phrase that is the same when read both forward and backward. Examples are: "bob," "sees," or "never odd or even" (ignoring spaces). Write a program whose input is a word or phrase, and that outputs whether the input is a palindrome.

Ex: If the input is:

bob

the output is:

bob is a palindrome

Ex: If the input is:

bobby

the output is:

bobby is not a palindrome

Hint: Start by just handling single-word input, and submit for grading. Once passing single-word test cases, extend the program to handle phrases. If the input is a phrase, remove or ignore spaces.

IN JAVA

Answer 1

import java.util.Scanner;
public class LabProgram {
    public static void main(String args[]){
        Scanner scanner = new Scanner(System.in);

        String s = scanner.nextLine();

        boolean flag = true;

        // i is the starting index of the string s
        // j is the ending index of the string s
        int i = 0, j = s.length()-1;

        // Checking the value if character at index i with the character at index j
        // If characters match, then move i to its next position and j t its previous position
        // If characters does not match then the string is not a palindrome.
        // In the case of does not match update the value of flag to false and break the loop
        while(i<j){
            if(s.charAt(i)==' '){
                i++;
            }
            else if(s.charAt(j)==' '){
                j--;
            }
            else {
                if(s.charAt(i)!=s.charAt(j)){
                    flag = false;
                    break;
                }
                i++;
                j--;
            }
        }

        if (flag) {
            System.out.println(s+" is a palindrome");
        } else {
            System.out.println(s+" is not a palindrome");
        }
    }
}