题解 | #求 1 - n 之间偶数的和#

#include <iostream>
using namespace std;

int main() {

    int n;
    cin >> n;
    int sum = 0;

    // write your code here......
    int i = 0;
    for (i = 0; i <= n; i++) {
        if (0 == (i % 2))
            sum += i;
    }

    cout << sum << endl;

    return 0;
}