Reverse a Number

Problem Statement

Write a Java program to reverse the digits of a given integer.

Examples

• Input: 12345 → Output: 54321
• Input: 0 → Output: 0
• Input: -123 → Output: -321

Solution

// O(log{10}(n))
import java.util.*;

public class Main{
    public static void main(String s[]){
        int res = reverseNumber(123);
        System.out.println(res);
    }

    public static int reverseNumber(int n){
        if(n==0) return 1;
        int reversedNumber=0;
        while(n>0){  
            int digit = n%10;
            reversedNumber = reversedNumber*10 + digit;
            n=n/10;
        }
        return reversedNumber;
    }
}