[leetcode]33. Search in Rotated Sorted Array

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

 

class Solution(object):
    def search(self, nums, target):
        l, r = 0 , len(nums)-1
        while l<=r :
            mid = (l+r)//2
            if nums[mid]== target:
                return mid
            elif nums[l] <= nums[mid] :
                if nums[mid] < target or (nums[mid] > target and nums[l] > target):
                    l = mid+1
                else :
                    r = mid-1
            else :
                if nums[mid] > target or(nums[mid] < target and nums[r] < target):
                    r = mid-1
                else :
                    l = mid +1
        return -1