LeetCode (power button) - Search in Rotated Sorted Array sort rotating array of python achieve search

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python achieve  Search in Rotated Sorted Array sort rotating array of search  

　　Chinese: Suppose ascending order according to the array was rotated in a previously unknown point.

　　(E.g., array [0,1,2,4,5,6,7] may become [4,5,6,7,0,1,2]).

　　Searching for a given target value, if the existence of the target array, its index returns, otherwise it returns -1.

　　You can assume that the array element does not exist in duplicate.

　　Your time complexity of the algorithm must be O (log n) level.

　　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 class Solution(object):
 2     def search(self, nums, target):
 3         """
 4         :type nums: List[int]
 5         :type target: int
 6         :rtype: int
 7         """
 8         start = 0
 9         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                 return mid
14             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[end]:
21                 if target > nums[mid] and target<=nums[end]:
22                     start = mid+1
23                     
24                 else:
25                     end = mid -1
26         return -1

 

Topic Source: stay button Exam