0540-Single-Element-in-a-Sorted-Array.py

'''
You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once. Find this single element that appears only once.

Follow up: Your solution should run in O(log n) time and O(1) space.



Example 1:

Input: nums = [1,1,2,3,3,4,4,8,8]
Output: 2

Example 2:

Input: nums = [3,3,7,7,10,11,11]
Output: 10


Constraints:
1 <= nums.length <= 10^5
0 <= nums[i] <= 10^5
'''
class Solution:
    def singleNonDuplicate(self, nums: List[int]) -> int:
        lo, hi = 0, len(nums) - 1
        while lo < hi:
            mid = (lo + hi) // 2

            if nums[mid] == nums[mid ^ 1]:
                lo = mid + 1
            else:
                hi = mid
        return nums[lo]