[leetcode: Python]189. Rotate Array

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题目：
Rotate an array of n elements to the right by k steps.

For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].

Note:
Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

注意：
尽量想出三种方法。

方法一：性能238ms

class Solution(object):    def rotate(self, nums, k):        """        :type nums: List[int]        :type k: int        :rtype: void Do not return anything, modify nums in-place instead.        """        while k > 0:            nums.insert(0,nums.pop())            k -= 1

方法二：性能75ms

class Solution(object):    def rotate(self, nums, k):        nums_copy = nums[:]        l = len(nums)        for i, n in enumerate(nums_copy):            nums[(i + k) % l] = n

方法三：性能66ms

class Solution(object):    def rotate(self, nums, k):        """        :type nums: List[int]        :type k: int        :rtype: void Do not return anything, modify nums in-place instead.        """        nums.reverse()        k%=len(nums)        nums[:k]=nums[:k][::-1]        nums[k:]=nums[k:][::-1]

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