第二道题是关于累加的sum
题目描述:
解决方案:
#include<stdio.h>
int sum(int n){
if(n%2)
return (n+1)/2*n;
else
return n/2*(n+1);
}
int main()
{
int n;
while(scanf("%d",&n) !=EOF){
printf("%d\n\n",sum(n));
}
return 0;
}