Project Euler | Problem 4 | Largest palindrome product

Problem Description :

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Find the largest palindrome made from the product of two 3-digit numbers?

Project Euler Problem 4

Concept :

A palindromic number or numeral palindrome is a number that remains the same when its digits are reversed. For example 99 is a palindrome but 89 is not.

Java Program :

	package com.javamultiplex.projecteuler;
	/**
	*
	* @author Rohit Agarwal
	* @category Project Euler Problems
	* @problem Largest palindrome product
	*
	*/
	public class Problem4 {
	public static void main(String[] args) {
	int maxThreeDigit = 999;
	int minThreeDigit = 100;
	int multInteger = 0;
	// lowest multiple of 2 three digit numbers
	int max = 100 * 100;
	for (int i = maxThreeDigit; i >= minThreeDigit; i--) {
	for (int j = i; j >= minThreeDigit; j--) {
	multInteger = i * j;
	// Checking multiplication is palindrome or not
	if (isPalindrome(multInteger)) {
	if (multInteger > max) {
	max = multInteger;
	break;
	}
	}
	}
	}
	System.out.println("Largest palindrom made from the product of two 3-digit numbers is: " + max);
	}
	private static boolean isPalindrome(int multInteger) {
	boolean result = false;
	String multString = null;
	StringBuffer multStringBuffer = null;
	// Converting Integer to String
	multString = String.valueOf(multInteger);
	/*
	* Converting String to StringBuffer, We want to reverse the string
	* thats why we have to use StringBuffer.
	*/
	multStringBuffer = new StringBuffer(multString);
	if (multString.equals(multStringBuffer.reverse().toString())) {
	result = true;
	} else {
	result = false;
	}
	return result;
	}
	}

view raw Problem4.java hosted with ❤ by GitHub

Output :

Output - Project Euler Problem 4

References :

https://projecteuler.net/problem=4

https://en.wikipedia.org/wiki/Palindromic_number

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html

https://docs.oracle.com/javase/7/docs/api/java/lang/StringBuffer.html

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Tags : Project Euler Problem 4, Solution in Java, Mathematics problems, Largest palindrome product, if else statement, for loop, String, StringBuffer.

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