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 = 1; i <= n; i ++) {
if ( (i&1) == 0) {
sum += i;
}
}
cout << sum << endl;
return 0;
}
