540. Single Element in a Sorted Array

https://leetcode.com/problems/single-element-in-a-sorted-array/description/

class Solution {
public:
    int singleNonDuplicate(vector<int>& nums) {
        // 1 1 2
        // 1 2 2
        // 1 1 2 3 3
        // 1 2 2 3 3
        // 1 1 2 2 3
        int l = 0, r = nums.size() - 1;
        while (l < r)
        {
            int m = l + (r - l) / 2;
            if (nums[m] == nums[m-1])
            {
                if (m % 2) l = m + 1;
                else r = m - 2;
            }
            else if (nums[m] == nums[m+1])
            {
                if (m % 2) r = m - 1;
                else l = m + 2;
            }
            else
                return nums[m];
        }
        return nums[l];
    }
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    /*
    
    int singleNonDuplicate(vector<int>& nums) {
        // 1 1 2
        // 3 4 4
        // 1 1 2 3 3
        // 1 1 2 2 3
        // 1 2 2 3 3
        int l = 0, r = nums.size() - 1;
        while (l < r)
        {
            int m = l + (r - l) / 2;
            if (nums[m] == nums[m+1])
            {
                if (m % 2)  // left odd
                    r = m - 1;
                else
                    l = m;
            }
            else if (nums[m] == nums[m-1])
            {
                if (m % 2)  // left odd
                    l = m + 1;
                else
                    r = m;
            }
            else
                return nums[m];
        }
        return nums[l];
    }
    */
};