[C++] Binary Search O(log N) | Use xor to maintain n and n+1 even, odd pair
\nint singleNonDuplicate(vector<int>& nums) {\n\tint start=0, end = nums.size()-1, mid;\n\twhile( start < end ) {\n\t\tmid = start + (end-start)/2;\n\t\tif( num
```\nint singleNonDuplicate(vector<int>& nums) {\n\tint start=0, end = nums.size()-1, mid;\n\twhile( start < end ) {\n\t\tmid = start + (end-start)/2;\n\t\tif( nums[mid] == nums[mid ^ 1] )\n\t\t\tstart = mid + 1;\n\t\telse\n\t\t\tend = mid;\n\t}\n\treturn nums[start];\n}\n```
['Binary Tree']