python旋转排序数组_LeetCode（力扣）——Search in Rotated Sorted Array 搜索旋转排序数组 python实现...

题目描述：

python实现Search in Rotated Sorted Array 搜索旋转排序数组

中文：假设按照升序排序的数组在预先未知的某个点上进行了旋转。

( 例如，数组 [0,1,2,4,5,6,7] 可能变为 [4,5,6,7,0,1,2] )。

搜索一个给定的目标值，如果数组中存在这个目标值，则返回它的索引，否则返回 -1 。

你可以假设数组中不存在重复的元素。

你的算法时间复杂度必须是 O(log n) 级别。

英文：Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

Your algorithm's runtime complexity must be in the order of O(log n).

1 classSolution(object):2 defsearch(self, nums, target):3 """

4 :type nums: List[int]5 :type target: int6 :rtype: int7 """

8 start =09 end = len(nums)-1

10 while start<=end:11 mid = (start + end)/2 #对于整数会自动省去小数部分

12 if nums[mid] ==target:13 returnmid14 if nums[mid]>=nums[start]:15 if target >= nums[start] and target<=nums[mid]:16 end = mid-1

17 else:18 start = mid + 1

19

20 if nums[mid] nums[mid] and target<=nums[end]:22 start = mid+1

23

24 else:25 end = mid -1

26 return -1

题目来源：力扣题库