题解 | 牛牛学数列

#include <stdio.h>

int main() 
{
    int n;
    int sum = 0;
    scanf("%d",&n);
    if(n%2!=0)
        {
            sum=(n-1)/2;
            sum*=(-1);
            sum+=n;
        }
    if(n%2==0)
        {
            sum=n/2;
            sum*=(-1);
        }
    printf("%d",sum);
}