POJ 3372 Candy Distribution

Candy Distribution

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 5261 Accepted: 2882

Description

N children standing in circle who are numbered 1 through N clockwise are waiting their candies. Their teacher distributes the candies by in the following way:

First the teacher gives child No.1 and No.2 a candy each. Then he walks clockwise along the circle, skipping one child (child No.3) and giving the next one (child No.4) a candy. And then he goes on his walk, skipping two children (child No.5 and No.6) and giving the next one (child No.7) a candy. And so on.

Now you have to tell the teacher whether all the children will get at least one candy?

Input

The input consists of several data sets, each containing a positive integer N (2 ≤ N ≤ 1,000,000,000).

Output

For each data set the output should be either "YES" or "NO".

Sample Input

23 4

Sample Output

YESNOYES

        首先要找规律，我先写了个辅助程序，查看哪些输入会得到YES的输出。代码如下：

#include"stdio.h"int main(){int i,n,cur;while(scanf("%d",&n)!=EOF){int a[400]={1,1};cur=2;for(i=1;i<1000;i++){cur=(cur+i)%n;a[cur]++;cur++;}printf("\n");for(i=0;i<n;i++){printf("%d : %d\n",i+1,a[i]);}}return 0;}

           输入一些测试用例后，我发现凡是能写成2^k (1<=k<=29)  的数，得到的输出都是"YES",其他数都得到"NO"。容易写出代码：

#include"stdio.h"int main(){int n;while(scanf("%d",&n)!=EOF){while( (n & 0x1) ==0 ){n>>=0x1;}n>>=0x1;printf("%s\n",n? "NO" : "YES");}return 0;}

yinjili3372Accepted164K0MSC++206B