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.
//Project euler problem 6
#include <iostream>
#include <cmath>
using namespace std;
unsigned int sum(int);
unsigned int sqsum(int);
int main()
{
cout << sum(100)*sum(100) - sqsum(100);
}
unsigned int sum(int n) // function for finding sum of n numbers
{
return (n*(n+1))/2;
}
unsigned int sqsum(int n) // function for finding sum of squares
{
return ((n)*(n+1)*(2*n +1 ))/6 ;
}
sqsum
is not correct. How many times does the loop execute? What is the initial value ofsum
? \$\endgroup\$ – Edward Jan 5 '15 at 11:44