WCW

# Solution: Project Euler Problem 6

The Problem:

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

My solution (in Java):

```
// Author: William Clausen
//
// Date: Jan 7, 2013
//
// This program solves Problem 6 form Project Euler.
/* Problem Statement:
* Find the difference between the sum of the squares of the first one hundred
* natural numbers and the square of the sum.
*/

import java.lang.Math; // For squaring numbers

public class Problem6 {

// Data members to store the number of natural numbers to use,
// the sum of the squares and the square of the sum.
public int sumSquare;
public int squareSum;
public int Num;

Problem6(int num)
{
Num = num;
sumSquare = 0;
squareSum = 0;
}

// Method that solves the problem and returns the result.
// The heavy lifting is done in the two helper functions,
// sumSquares(int) and squaredSum(int).
public int solve()
{
sumSquare = sumSquares(Num);
squareSum = squaredSum(Num);

return squareSum - sumSquare;
}

// This function computes the sum of the squares of the natural numbers
// from 1 to num.
private int sumSquares(int num)
{
int sum = 0;

for (int i = 1; i <= num; i++) {
sum += (int) Math.pow(i,2);
}

return sum;
}

// This function computes and returns the square of the sum of the natural
// numbers from 1 to num.
private int squaredSum(int num)
{
int totalSum = (num)*(num+1);
totalSum = totalSum/2;
totalSum = (int) Math.pow(totalSum, 2);