Question

The main method from this class contains code which is intended to fill an array of length 10 with the sums of the first n natural numbers, then print the value of the number in the array at the index entered by the user. For example if the user inputs 3 then the program should output 1 + 2 + 3 = 6, while if the user inputs 6 then the program should output 1 + 2 + 3 + 4 + 5 + 6 = 21. Debug this code so it works as intended.

I've done most of it, but one of the grade checks is returning fail, but I'm not sure what it's asking for. Below is the feedback.
DESCRIPTION
This test case checks that the value printed when the last valid index for the array is input is correct.
MESSAGE
Make sure your code sets each value in the array to the sums of the n natrual numbers up to and including the last valid index of the array.
Code is below
import java.util.Scanner;
public class U6_L1_Activity_Two
{
public static void main(String[] args)
{

int[] h = new int[10];

h[0] = 0;
h[1] = h[0] + 1;
h[2] = h[1] + 2;
h[3] = h[2] + 3;
h[4] = h[3] + 4;
h[5] = h[4] + 5;
h[6] = h[5] + 6;
h[7] = h[6] + 7;
h[8] = h[7] + 8;
h[9] = h[8] + 9;

Scanner scan = new Scanner(System.in);
int i = scan.nextInt();
if (i > 0 && i <= 9)
System.out.print(h[i]);
}
}

Answer 1

To fix the code, remove the individual assignments to the array elements and add a for loop to calculate the sum of the first n natural numbers and assign each value to the corresponding index in the array.

The code provided does not fill the array with the correct values according to the given requirements. To fix this, you need to use a loop to calculate the sum of the first n natural numbers and assign each value to the corresponding index in the array.

Remove the individual assignments to the array elements (h[0], h[1], etc.).

Add a for loop that iterates from 0 to n-1, where n is the input from the user. Inside the loop, calculate the sum of the first i+1 natural numbers and assign it to the array element at index i.

Finally, after the loop, print the value in the array at the index entered by the user.

Here's the modified code:

import java.util.Scanner;
public class U6_L1_Activity_Two {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int[] h = new int[10];
int sum = 0;
for (int i = 0; i < n; i++) {
sum += (i + 1);
h[i] = sum;
}
if (n > 0 && n <= 10) {
System.out.print(h[n - 1]);
}
}
}