hdu2053 Switch Game（C语言）

Problem Description

There are many lamps in a line. All of them are off at first. A series of operations are carried out on these lamps. On the i-th operation, the lamps whose numbers are the multiple of i change the condition ( on to off and off to on ).

 

Input

Each test case contains only a number n ( 0< n<= 10^5) in a line.

 

Output

Output the condition of the n-th lamp after infinity operations ( 0 - off, 1 - on ).

 

Sample Input

15

 

Sample Output

10
Hint
hint
 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.

 

Author

LL

C语言AC代码

#include<stdio.h>#include<math.h>int main(){    int n;    double t;    while(scanf("%d",&n)!=EOF)    {        t=sqrt(n*1.0);        if(t==(int)t)            printf("1\n");        else            printf("0\n");    }    return 0;}

思路：1   模拟所有情况，超时

　　　　 2   n的的状态由n的约数个数决定。奇数时，开启，偶数时，关闭。

               3    约数的个数为奇数时，n为平方数（平方数的两个约数相同），由此，判断n是否为平               方数即可。