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Java

Posted by Michael Singleton
Michael Singleton
6,253 Points

What is the difference between the sum and square of a 100 numbers

Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

In Swift, this could look like:

var squareOfSum = 0
var sumOfSquare = 0
var difference = 0

for var i = 1; i < 101; i++ {
    squareOfSum += i
    sumOfSquare += i * i
}

squareOfSum = squareOfSum * squareOfSum
difference = squareOfSum - sumOfSquare
println(difference)

I threw that together because I had a Playground open.

Translating that into Java shouldn't be too difficult - the concepts are precisely the same. Let me know if you struggle - I'll dig out the javac compiler and work it through.

Steve.

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Michael,

What's your question here? Is this one of the challenges?

If I was asked to write the code for this, I would start with a for loop to loop through 1 to 100. Inside the loop, I would add up each one cumulatively. This will be for the square of the sums. I would also cumulatively add together the square of each number - this will be the su of the squares.

Then, once the loop has finished, you can take the difference of the square of the sum and the sum of the square.

Hope that helps a little?

Steve.

Michael Hess
Michael Hess
24,512 Points

It's problem 6 on project Euler

problem 6