Most Frequently asked Coding Questions

Here I will be mainly focusing on OnCampus technical Interviews because I have attended a couple of them. and I observed these are common questions to check you know the basics of coding or not.

1.To swap two numbers without using an extra variable

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
         int a,b;
         System.out.println("Enter two numbers");
         Scanner sc = new Scanner(System.in);
         a = sc.nextInt();
         b = sc.nextInt();
         //logic to swap without using extra variable.
         a = a+b;
         b = a - b;
         a = a - b;
         System.out.println("After swapping: "+ "a="+ a +"," + "b="+ b );
    }
}

2.Check given number is Amstrong Number or not

To Know more about Amstrong Number refer the link here

import java. util.*;
public class Main
{
    public static void main(String[] args)
    {
         int a;
          Scanner sc = new Scanner(System.in);
         System.out.println("Enter the number");
         a = sc.nextInt();
         //to find length or number of digits in number
         int num = a;
         int len = 0;
         int rem;
         while(num!=0)
         {
             rem = num%10;
             num = num/10;
             len++;
         }
        //logic to check Armstrong number or Not 

        int sum = 0;
        num = a;
        while(num!=0)
        {
           rem = num%10;
           int mul= 1;
           for(int i=0;i<len;i++)
           {
               mul = mul * rem;
           }
           sum +=mul;
           num= num/10;
        }
        if(sum==a)
        {
            System.out.println("Amstrong Number");
        }
        else{
            System.out.println("Not an Amstrong number");
        }
    }
}

3.To find out the Fibonacci value

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        int n;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number");
        n = sc.nextInt();
        int n1 = 0 , n2 = 1;
        int res = 0;
        for(int i=2;i<=n;i++)
        {
            res = n1+n2;
            n1 = n2;
            n2 = res;
        }
        System.out.println("Fib of n is " + res);

    }
}

4.to print Fibonacci series

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        int n;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number");
        n = sc.nextInt();
        int n1 = 0 , n2 = 1;
        int res = 0;
        System.out.print("Fibonacci series is " + n1 + " " + n2 + " ");
        for(int i=2;i<=n;i++)
        {
            res = n1+n2;
            n1 = n2;
            n2 = res;
            System.out.print(res + " ");
        }


    }
}

5.Factorial of a number

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        int n;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number");
        n = sc.nextInt();
        int fact = 1;
        for(int i=1;i<=n;i++)
        {
            fact = fact * i;
        }
        System.out.println("Factorial of n is:" + fact);

    }
}

6.LCM and GCD of a number

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        int n1,n2;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number");
        n1 = sc.nextInt();
        n2 = sc.nextInt();
        int numerator,denominator;
        if(n1>n2)
        {
            numerator = n1;
            denominator = n2;
        }
        else{
            numerator = n2;
            denominator = n1;
        }
        int rem = numerator%denominator;
        while(rem!=0)
        {
            numerator = denominator;
            denominator = rem;
            rem = numerator%denominator;
        }
        System.out.println("HCF of numbers:" + denominator );
        int lcm = (n1*n2)/denominator;
            System.out.println("LCM of numbers:" + lcm );
    }
}

7.Program to check leap year or not

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        int n1,n2;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the year");
        int year = sc.nextInt();
        if(year%4==0)
        {
            //check for century year
            if(year%100==0)
            {
                //check it is divisible by 400
                if(year%400==0)
                {
                    System.out.println("Leap year");
                }
                else{
                     System.out.println("Not a leap year");
                }
            }
            else{
                System.out.println("Leap year");
            }
        }
        else{
            System.out.println("Not a leap year");
        }

    }
}

I hope this helps for your OnCampus technical Interviews.

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