Single Element in a Sorted Array

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:

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

Example 2:

1
2
Input: nums = [3,3,7,7,10,11,11]
Output: 10

Constraints:

1 <= nums.length <= 10^5
0 <= nums[i] <= 10^5

Solution:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
class Solution {
    public int singleNonDuplicate(int[] nums) {
        int l = 0;
        int r = nums.length - 1;
        while (l < r) {
            int mid = l + (r - l) / 2;
            boolean isEven = (r - mid) % 2 == 0;
            if (nums[mid] == nums[mid - 1]) {
                if (isEven) {
                     r = mid - 2;
                } else {
                     l = mid + 1;
                }
            } else if (nums[mid] == nums[mid + 1]) {
                if (isEven) {
                   l = mid + 2;
                } else {
                    r = mid - 1;
                }
            } else {
                return nums[mid];
            }
        }
        return nums[l];
    }
}