540. Single Element in a Sorted Array | LeetCode Solution

Raunit Verma November 28, 2021

540. 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.

Return the single element that appears only once.

Your solution must 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 <= 105
0 <= nums[i] <= 105

The solution to the above question

class Solution {
public:
    int singleNonDuplicate(vector<int>& nums) {
        int L=0, R=0, mid;
        for(int i=0; i<nums.size(); i++){
            mid=(L+R)/2;
            bool flag=(L-R)%2;
            if(nums[mid]==nums[mid+1]){
                R=mid-1;
            }
            else if( nums[mid]==nums[mid-1]){
                R=mid+1;
            }
            else {
                return nums[mid];
            }
        }
        return nums[0];
    }
};