题解 | 牛牛学数列
牛牛学数列
https://www.nowcoder.com/practice/0b97367cd2184c12a0e02f7c223aee11
#include <stdio.h>
int main()
{
int n;
scanf("%d",&n);
int i;
int flag = 1;
int sum = 0;
for(i = 1; i <= n; i++)
{
sum += flag * i;
flag = -flag;
}
printf("%d",sum);
return 0;
}