33-Search-in-Rotated-Sorted-Array.md

33. Search in Rotated Sorted Array

You are given an integer array nums sorted in ascending order, and an integer target.

Suppose that nums 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]).

If target is found in the array return its index, otherwise, return -1.

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

Example 3:

Input: nums = [1], target = 0
Output: -1

Constraints:

• 1 <= nums.length <= 5000
• -10^4 <= nums[i] <= 10^4
• All values of nums are unique.
• nums is guranteed to be rotated at some pivot.
• -10^4 <= target <= 10^4

Solution

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        left, right = 0, len(nums)-1
        while left < right:
            mid = (left + right) // 2
            if nums[mid] > nums[right]:
                if target <= nums[right] or target > nums[mid]:
                    left = mid + 1
                else:
                    right = mid
            else:
                if nums[mid] < target <= nums[right]:
                    left = mid + 1
                else:
                    right = mid
        return -1 if left == right and target != nums[left] else left

A rotated sorted array is a sorted array nonetheless. Go, binary search!