| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 6012 | Accepted: 3341 |
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
2 3 4
Sample Output
YES NO YES
【思路】找规律，是2的指数输出yes否则no
#include<iostream> #include<stdio.h> #include<string.h> using namespace std; int main() { long long n; while(~scanf("%lld",&n)) { while(n) { if(n&1) break;//二进制数最右位为1时，若n为1，则为2的指数，否则不能除2了也要退出 n>>=1;//相当于每次除2 } if(n==1) printf("YES\n"); else printf("NO\n"); } return 0; }
原文：http://www.cnblogs.com/iwantstrong/p/5838042.html