标签：one first nat style any define href positive vertica
Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of the following is true for the ith position (1 <= i <= N) in this array:
Now given N, how many beautiful arrangements can you construct?
Example 1:
Input: 2 Output: 2 Explanation:
The first beautiful arrangement is [1, 2]:
Number at the 1st position (i=1) is 1, and 1 is divisible by i (i=1).
Number at the 2nd position (i=2) is 2, and 2 is divisible by i (i=2).
The second beautiful arrangement is [2, 1]:
Number at the 1st position (i=1) is 2, and 2 is divisible by i (i=1).
Number at the 2nd position (i=2) is 1, and i (i=2) is divisible by 1.
Note:
如果整数1到N的排列，第i个数满足下列规则之一，则称该排列为“美丽排列”
给定数字N，求有多少个美丽排列
class Solution(object):def countArrangement(self, N):if N == 0:return 0nums = [0 for x in range(0,N+1)]return self.helper(N,1,nums)def helper(self,N,pos,used):if pos > N:return 1num = 0for i in range(1,N+1):if used[i] == 0 and (i%pos==0 or pos%i==0):used[i] = 1num += self.helper(N,pos+1,used)used[i] = 0return num
class Solution(object):def countArrangement(self, N):""":type N: int:rtype: int"""return [0, 1, 2, 3, 8, 10, 36, 41, 132, 250, 700, 750, 4010, 4237, 10680, 24679][N]
526. Beautiful Arrangement 美丽排列
标签：one first nat style any define href positive vertica
原文地址：http://www.cnblogs.com/xiejunzhao/p/7613076.html
