33. Search in Rotated Sorted Array

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:

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

Example 2:

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Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1

Code：

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class Solution(object):
    def search(self, nums, target):
        lo, hi = 0, len(nums) - 1
        while lo < hi:
            mid = (lo + hi) / 2
            # 判断target在前还是在后
            if (nums[0] > target) ^ (nums[0] > nums[mid]) ^ (target > nums[mid]):
                lo = mid + 1
            else:
                hi = mid
        return lo if target in nums[lo:lo+1] else -1y