Problem 6

Problem

The sum of the squares of the first ten natural numbers is,

1² + 2² + ... + 10² = 385

The square of the sum of the first ten natural numbers is,

(1 + 2 + ... + 10)² = 55² = 3025

Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 385 = 2640.

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

Code

#include <iostream>
using namespace std;

int main()
{
    long long a = 0;
    long long b = 0;
    for (long long i = 1; i <= 100; i++)
    {
        a += i*i;
        b += i;
    }
    cout << b*b - a << endl;
}