      "    * If you get to the root (ie node.parent is None), return None\n",
      "    * Else, return the parent\n",
      "    \n",
      "Complexity:\n",
      "* Time: O(n)\n",
      "* Space: O(h), where h is the height of the tree"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
 
</s>
    "* Time: O(h), where h is the height of the tree\n",
    "* Space: O(h), where h is the recursion depth (tree height), or O(1) if using an iterative approach"
      "    * If you get to the root (ie node.parent is None), return None\n",
      "    * Else, return the parent\n",
      "    \n",
      "Complexity:\n",
    "* Time: O(h), where h is the height of the tree\n",
    "* Space: O(h), where h is the recursion depth (tree height), or O(1) if using an iterative approach"
    "* Time: O(h), where h is the height of the tree\n",
    "* Space: O(h), where h is the recursion depth (tree height), or O(1) if using an iterative approach"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
keep keep keep keep replace replace keep keep keep keep keep
 Polish bst successor challenge and solution (#82)

Update constraints, test cases, tests, algorithm discussion, and code.
graphs_trees/bst_successor/bst_successor_solution.ipynb