sum初始化为0,不是1
while(i++<=n){
if(i%2!=0) {
continue;
}
sum+=i;
}
#include<stdio.h>
int main()
{
int n,i=1,sum=0;
scanf("%d",&n);
while(i<=n)
{
if(i%2==0)
sum=sum+i;
i++;
}
printf("%d\n",sum);
return 0;
}