Palindrome Program

Overview

This Java program provides a variety of features related to palindromes, allowing users to:

1. Check if a word is a palindrome.
2. Find palindromes in a paragraph.
3. Check if a number is a palindrome.
4. Generate palindromic numbers within a range.
5. Find the longest palindromic substring in a string.
6. Find all palindromic substrings in a string.

How It Works

When you run the program, you will be presented with a menu of options. Simply select the number corresponding to the operation you wish to perform, and follow the prompts to provide input.

Features

1. Check if a Word is a Palindrome

• Description: Prompts the user to enter a word and checks whether it reads the same backward as forward.
• Input Example: radar
• Output Example: Is the word a palindrome? true

2. Find Palindromes in a Paragraph

• Description: Takes a paragraph and identifies all the palindromic words within it.
• Input Example: Madam Arora teaches malayalam.
• Output Example:

  Palindromes found in the paragraph:
  madam
  arora
  malayalam
  

3. Check if a Number is a Palindrome

• Description: Prompts the user to enter a number and determines if it is a palindrome.
• Input Example: 12321
• Output Example: Is the number a palindrome? true

4. Generate Palindromic Numbers Within a Range

• Description: Asks for a range (start and end) and prints all palindromic numbers within that range.
• Input Example: Start: 10, End: 200
• Output Example:

  Palindromic numbers within the range:
  11
  22
  33
  ...
  191
  

5. Find the Longest Palindromic Substring in a String

• Description: Identifies the longest substring within a given string that is a palindrome.
• Input Example: babad
• Output Example: The longest palindromic substring is: bab

6. Find All Palindromic Substrings in a String

• Description: Finds and lists all palindromic substrings in the given input string.
• Input Example: aaa
• Output Example:

  Palindromic substrings found:
  a
  aa
  aaa
  

Code Structure

Main Class: Palindrome

• Handles the menu and user input.
• Calls appropriate methods based on user choice.

Methods:

1. CheckPalindrome(String word): Checks if a given string is a palindrome.
2. cleanWord(String word): Cleans a string by removing non-alphanumeric characters and converting to lowercase.
3. reverse(String s): Reverses the input string.
4. findPalindromes(String paragraph): Extracts palindromic words from a paragraph.
5. generatePalindromicNumbers(int start, int end): Prints all palindromic numbers within a range.
6. longestPalindrome(String s): Finds the longest palindromic substring in a string.
7. findAllPalindromicSubstrings(String s): Identifies all palindromic substrings in a string.
8. expandAroundCenter(String s, int left, int right, Set<String> palindromes): Helper method to identify substrings that are palindromes.

Example Usage

1. Compile the program:

   javac Palindrome.java
   

2. Run the program:

   java Palindrome
   

3. Follow the on-screen menu to interact with the program.

Requirements

• Java Development Kit (JDK) installed on your system.
• Basic knowledge of running Java programs from the command line.

Notes

• This program ignores case and special characters when checking for palindromes.
• It efficiently identifies palindromic substrings using the center expansion technique.

Feel free to explore the code and adapt it to your needs!