Problem
https://projecteuler.net/problem=6
The sum of the squares of the first ten natural numbers is,
\[1^2 + 2^2 + ... + 10^2 = 385\]The square of the sum of the first ten natural numbers is,
\[(1 + 2 + ... + 10)^2 = 55^2 = 3025\]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.
Answer: 25164150
Solution
#include <iostream>
int sum_squares(size_t size)
{
int sum_square = 0;
int square_sum = 0;
for(size_t i = (size+1); --i ;)
{
sum_square += (i*i);
square_sum += i;
}
return ((square_sum*square_sum) - sum_square);
}
int main( int argc , char* argv[])
{
std::cout << "Answer: " << sum_squares(100) << std::endl;
}