题解 | #求 1 - n 之间偶数的和#

#include <array>
#include <iostream>
#include <vector>
using namespace std;

int main() {

    int n;
    cin >> n;
    int sum = 0;
    vector<int> arr;
    // write your code here......
    for (int i = 1; i<100000; i++){
        if (i<= n && i%2 == 0){sum += i;}
        if (i>n){break;}
    }






    cout << sum << endl;

    return 0;
}