6問目。

プログラム Project Euler

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 = 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.

#include <iostream>

using namespace std;

int main()
{
	
	unsigned long long int sum=0;
	unsigned long long int sq=0;
	for(int i=1;i<=100;i++)
	{
		sum+=(i*i);

		sq+=i;
	}
	cout<<(sq*sq)-sum<<endl;
}