Question

David is following an exercise regime where on first,
second and third day he works out for 1, 2 and 3 minutes.
After 3 days, his workout duration is sum of the 3 previous days.
What is his workout duration (in minutes) after ‘n’ days, where n is greater than 4.​

Answer 1

Answer:

import java.util.ArrayList;

import java.util.Scanner;

public class David

{

   public static void main(String[] args)

  {

     Scanner sc = new Scanner(System.in);

int n= sc.nextInt();

if(n<4)

      {

           System.out.println("Invalid");

       }

       else

      {

           ArrayList<Integer> arr=new ArrayList<>();

           arr.add(0,1);

           arr.add(1,2);

           arr.add(2,3);

           int x=0;

           for(int i=3;i<n;i++)

            {

              x =arr.get(i-3)+arr.get(i-2)+arr.get(i-1);

              arr.add(i,x);

           }

           System.out.println(arr.get(n-1));

       }

   }

}

Explanation: