Write a program to find sum of squares of all numbers given the following conditions?

Question

Given two numbers n1 and n2 such that n2>n1, find sum of squares of all numbers from n1 to n2 (including n1 and n2).

My Approach:

I tried to solve the problem using a for loop iterated from n1 to n2 but I am getting wrong answer

Below is my function for the code:

public int computeSumofSquares (int n1, int n2) 
{
    int sum=0;
    if(n2>n1)
    {
        for(int i=n1;i<=n2;i++)
        {
            sum=((sum)+(n1*n1));
        }
    }
    return sum;
    //write your code here

}

For the Input

Parameters  Actual Output   Expected Output
'8' '10'    192             245

Answer 1

You are squaring n1 on every iteration. Instead you should square i . As a short form of sum=((sum)+(i*i)); you can write sum += i * i;

Answer 2

Change sum=((sum)+(n1*n1)); to sum=((sum)+(i*i)); as i is the value incrementing.

Answer 3

In your loop i changes every time but in your statement sum=((sum)+(n1*n1)); nothing changes and each time in your example you are summing 8^2 and the result would be 8*8 + 8*8 + 8*8 = 192.

As everybody said if you change n1 to i in that statement, something like sum=sum+i*i , then you will get the result you want.

Answer 4

As others have already stated, you were always using the lower bound of your interval n1 to calculate sum (instead of your loop variable i ).

For completeness, I'm posting a java8 solution:

int n1 = 8;
int n2 = 10;
int sumOfSquares = IntStream.rangeClosed(n1, n2).map(i -> i * i).sum();

System.out.println(sumOfSquares); // 245

Please check IntStream docs for further reference.