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......
    for(int i = 0; i<=n; i+=2)
    {
        sum+=i;
    }

    cout << sum << endl;
    
    return 0;
}