(540) Single Element in a Sorted Array - O(log n)

class Solution {
public:
    int singleNonDuplicate(vector<int>& nums){
        int n = nums.size();
        int low = 0;
        int high = n-2;
        while(low <= high){
                int mid = (low + high)/2;
                if(mid % 2 != 0){
                    if(nums[mid] == nums[mid-1])
                        low = mid + 1;
                    else
                        high = mid - 1;
                }
                else{
                     if(nums[mid] == nums[mid+1])
                         low = mid+1;
                     else
                         high = mid-1;
                }
            }
        return nums[low];
    }
};