题解 | #牛牛学数列#

知识点：

循环控制：循环控制

数学

#include <iostream>
using namespace std;

int main() {
    int n = 0;
    int sum = 0;
    cin >> n;

    if (n % 2 == 0) {
        sum = -n / 2;
    } else {
        sum = (n + 1) / 2;
    }

    cout << sum;

    return 0;
}

/*
int main() {
    int n = 0;
    int flag = 1;
    int sum = 0;
    cin >> n;

    for (int i = 1; i <= n; i++) {
        sum += i * flag;
        flag *= (-1);
    }

    cout << sum;

    return 0;
}
*/