33_Search_in_Rotated_Sorted_Array.py

"""
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).

Example 1:

Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4

Example 2:

Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1
可以先找到转折点，然后二分查找

"""

class Solution(object):
    def search(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        if not nums:return -1
        pivot = nums.index(max(nums))#不知道max函数的
        if target >= nums[0] and target <=  nums[pivot]:
            low, high = 0,pivot
        else:
            low, high = pivot + 1,len(nums) - 1
        while low <= high:
            mid = (low + high) // 2
            if nums[mid] == target:
                return mid
            elif nums[mid] > target:
                high = mid - 1
            else:
                low = mid + 1
        return - 1

        low, high = 0, len(nums)
        while low <= high:
            mid = (low + high) // 2
            if nums[mid] == target:
                return mid
            elif nums[mid] > target:
                high = mid - 1
            else:#nums[mid] < target
                low = mid + 1





so = Solution()
nums = [4,5,6,7,0,1,2]; target = 0
nums = []; target = 1
print(so.search(nums, target))