CODEWITHSUNDEEP
java
George
George

Reputation: 1

Finding palindrome numbers

I'm trying to make a java code that displays the largest palindrome number made from the product of two 3-digit numbers. It outputs all palindromes, not in numerical order. I don't know why. Please help! Here's my code:

`class Scratch { public static void main(String[] args) { int dig1, dig2, dig3, dig4, dig5, dig6, product;

    for (int i =999; i>100; i--){
        for (int j =999; j>=i;j--){
            product = j*i;
            dig1= product/100000;
            dig2= (product/10000)%10;
            dig3= (product/1000)%10;
            dig4= (product/100)%10;
            dig5= (product/10)%10;
            dig6= (product%10);
            if ((dig1==dig6) && (dig2==dig5) && (dig3==dig4)){
                System.out.println((product));
                break;
            }

        }

    }
}}

Upvotes: 0

Views: 182

Answers (2)

Yuvraj Sharma
Yuvraj Sharma

Reputation: 1

//Here is the simple solution

public class Test {

public static void main(String[] args) throws Exception{
 
int x=4547454;
int temp=x;
String s="";

while(temp>0){
  s=s+temp%10;
  temp=temp/10;
}
System.out.println(s);
if(Integer.valueOf(s) == x)
System.out.println("palindrome");
else
System.out.println("not palindrome");
}

}

Upvotes: 0

WJS
WJS

Reputation: 40057

A couple suggestions.

  • to avoid duplicate pairs, you can do this.
for (int i = 999; i > 100; i--) {
    for (int k = i; k > 100; k--) {
  • To reverse the digits of a number, you can do it in a while loop.
    Below, val is the product of i and j.
int rev = 0;
int temp = val;
while (temp != 0) {
    rev = rev * 10 + temp % 10;
    temp /= 10;
}

then

if (rev == val) { is a palindrome?
   ...
}

As each number is found, you can find the largest as follows. At the start, initialize max to Integer.MIN_VALUE. Then do the following:

int savei = 0;
int savej = 0;
int max = Integer.MIN_VALUE;

// then later as you find the palindromes.
if (max < val) {
   max = val;
   savei = i
   savej = j;
}

At the end, you will have the largest palindrome and the three digit numbers that divide it.

Upvotes: 1

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