Search in Rotated Sorted Array (Using Double Binary Search) | LeetCode 33

In this episode, we solve Leetcode problem 33, where we search for a target number in a rotated and sorted array and return it's index. We achieve an O(log n) solution using pointers in a binary search. We accomplish this using Python 3. Watch and enjoy.

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There is an integer array nums sorted in ascending order (with distinct values).

Prior to being passed to your function, nums is rotated at an unknown pivot index k) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].

Given the array nums after the rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.

You must write an algorithm with O(log n) runtime complexity.

Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4

Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1

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