Codeforces Beta Round #51 A. Flea travel 水题

A. Flea travel

Time Limit: 20 Sec

Memory Limit: 256 MB

题目连接

http://codeforces.com/contest/55/problem/A

Description

A flea is sitting at one of the n hassocks, arranged in a circle, at the moment. After minute number k the flea jumps through k - 1hassoсks (clockwise). For example, after the first minute the flea jumps to the neighboring hassock. You should answer: will the flea visit all the hassocks or not. We assume that flea has infinitely much time for this jumping.

Input

The only line contains single integer: 1 ≤ n ≤ 1000 — number of hassocks.

Output

Output "YES" if all the hassocks will be visited and "NO" otherwise.

Sample Input

1

Sample Output

YES

HINT

题意

有一个环，有n个位置

一开始你在0，然后往前跳，第一次跳n-1，第二次跳n-2，第三次跳n-3.....直到跳到不能跳为止

问你是否能够遍历所有的位置

题解：

数据范围只有1000，直接暴力就好了

代码：

#include<iostream>
#include<stdio.h>
using namespace std;

int p[1005];
int main()
{
int n;scanf("%d",&n);
p[0]=1;
int ans = 1;
int tmp = 0;
for(int i=n-1;i>0;i--)
{
tmp = (tmp + i)%n;
if(p[tmp]==0)
{
p[tmp]=1;
ans++;
}
}
if(ans==n)printf("YES\n");
else printf("NO\n");
}