33_SearchInRotatedSortedArray.py

# coding: utf8


"""
    题目链接: https://leetcode.com/problems/search-in-rotated-sorted-array/description.
    题目描述:

    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.

"""


class Solution(object):
    def search(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        if not nums:
            return -1

        left = 0
        right = len(nums) - 1
        # 每次确定一半有序
        while left <= right:
            mid = left + (right - left) // 2
            if nums[mid] == target:
                return mid
            if nums[mid] < nums[right]:
                if nums[mid] < target <= nums[right]:
                    left = mid + 1
                else:
                    right = mid - 1
            else:
                if nums[left] <= target < nums[mid]:
                    right = mid - 1
                else:
                    left = mid + 1

        return -1