Multiples of 3 and 5 Problem & Solution
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below 1000.
See the multiples of 3 and 5 problem on Project Euler.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
#include <iostream>
#include <vector>
using namespace std;
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
int main() {
int sum = 0;
for (int i = 0; i < 1000; ++i) {
if (i % 3 == 0 || i % 5 == 0) {
sum += i;
}
}
cout << sum << endl;
}