Most Frequently asked Coding Questions
Published: 2021-09-21 10:20:29

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](https://www.geeksforgeeks.org/program-for-armstrong-numbers/)
``` 
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.