leetcode_gym/_problems/insertIntoBST.md

layout, title, last_solved, category, leetcode_url, status

layout	title	last_solved	category	leetcode_url	status
page	Insert into BST		tree	https://leetcode.com/problems/insert-into-a-binary-search-tree	Attempted

Problem

Given the root node of a binary search tree (BST) and a value to be inserted into the tree, insert the value into the BST. Return the root node of the BST after the insertion. It is guaranteed that the new value does not exist in the original BST.

Note that there may exist multiple valid ways for the insertion, as long as the tree remains a BST after insertion. You can return any of them.

For example, 

Given the tree:
        4
       / \
      2   7
     / \
    1   3
And the value to insert: 5
You can return this binary search tree:

         4
       /   \
      2     7
     / \   /
    1   3 5
This tree is also valid:

         5
       /   \
      2     7
     / \   
    1   3
         \
          4

Solution

{% highlight python %}

def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
    
    if not root:
        return TreeNode(val)
    
    # root is bigger, it goes on left side
    if root.val > val:
        if not root.left:
            root.left = TreeNode(val)
        else:
            self.insertIntoBST(root.left, val)
    
    else:
        if not root.right:
            root.right = TreeNode(val)
        else:
            self.insertIntoBST(root.right, val)
    
    return root

{% endhighlight %}

---

{% highlight python %}

{% endhighlight %}