[算法题] Search in Rotated Sorted Array ii

题目内容

题目来源：LeetCode

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).

Write a function to determine if a given target is in the array.

The array may contain duplicates.

题目思路

本题难度：medium

这个题目是基于上一道题Search in Rotated Sorted Array改进的。在上一道题当中，nums[start]和nums[mid]的判断中，将<和=是联合在一起进行判断的。在本题当中，假如nums[start]==nums[mid]，那么将start+=1，将start转移到不等的地方。

Python代码

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