Re:题意：有无限多的电灯排成一列，一开始都是关，操作无限多次，第i次操作会把编号为i和i的倍数的电灯改变状态。问最后第i盏电灯的状态是开还是关    //后边有数据。。。

#include
    
     int main(){
        int a,b,i;    while(scanf("%d",&a)!=EOF)    {
            b=0;        for(i=1;i<=a;i++)        {
                if(a%i==0)            b++;        }        if(b%2==1)//开关变化（1 0 1 0 1 0.......）;        printf("1\n");        else        printf("0\n");    }    return 0;}
    

Consider the second test case:

           The initial condition : 0 0 0 0 0 …

    After the first operation : 1 1 1 1 1 …

After the second operation : 1 0 1 0 1 …

   After the third operation : 1 0 0 0 1 …

 After the fourth operation : 1 0 0 1 1 …

    After the fifth operation : 1 0 0 1 0 …

The later operations cannot change the condition of the fifth lamp any more. So the answer is 0.