LeetCode重点题系列之【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:

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

说实在话，我真的非常讨厌这样搞范围的题，基本思路二分，没什么好说的。关键在于首先要确定是在左大段（nums[left]<=nums[mid]），还是右大段(nums[mid]<=nums[right])，然后在看 target是什么范围。

class Solution(object):
    def search(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        left=0
        right=len(nums)-1
        while left<=right:
            mid=left+(right-left)/2
            if nums[mid]==target:
                return mid
            elif nums[mid]>=nums[left]:
                if nums[left]<=target