0540-single-element-in-a-sorted-array.java

/*
----------------------------------
  Time Complexity: O(log(n))
  Space Complexity: O(1)
---------------------------------*/  

class Solution {
    public int singleNonDuplicate(int[] nums) {
        int l = 0;
        int r = nums.length-1;

        while(l <= r){
            int m = l + (r-l)/2 ;  
            if((m - 1 < 0 || nums[m-1] != nums[m]) && (m + 1 == nums.length || nums[m] != nums[m+1]))
                return nums[m];

            int leftSize = 0;
            leftSize = (nums[m-1] == nums[m])? m-1 : m;
            if(leftSize % 2 == 1)
                r = m - 1;
            else
                l = m + 1;    
        }
        return -1;
    }
}