描述
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.
分析
如果允许开新数组，那就太简单了，当然我们要找空间O(1)的解法。把原数组分为两段，分别翻转，然后把数组整体翻转，就得到了结果。
代码
Python
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| 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.
"""
k = (len(nums) - k) % len(nums)
self.reverse(nums, 0, k - 1)
self.reverse(nums, k, len(nums) - 1)
self.reverse(nums, 0, len(nums) - 1)
def reverse(self, nums, x, y):
k = (y - x + 1) / 2
for i in xrange(k):
nums[x + i], nums[y - i] = nums[y - i], nums[x + i]
|