Project Euler question 10 problem solution

Summation of primes

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

Prime specific sum

All primes less than 10 and is 2 + 3 + 5 + 7 = 17.

Find all primes less than two million and.

Problem-solving ideas

Not a particularly good idea, under the milk can think of is calculated to enumerate all the prime numbers less than 2 million, then seek these primes.

Codes are as follows:

#include <bits/stdc++.h>
using namespace std;
bool check(int a) {
    if (a < 2) return false;
    for (int i = 2; i*i <= a; i ++)
        if (a % i == 0) return false;
    return true;
}
long long sum;
int main() {
    for (int i = 2; i < 2000000; i ++)
        if (check(i))
            sum += i;
    cout << sum << endl;
    return 0;
}

Get answers to \ (142 913 828 922 \) .