leetcode：701. Insertion in binary search tree [BST insertion]

analysis

Be careful ,bst Insert directly into leaves
There is no need to refactor like delete
This needs attention

ac code

# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
    def insertIntoBST(self, root: TreeNode, val: int) -> TreeNode:
        #  Insert directly into the leaf without refactoring 
        if not root: return TreeNode(val)

        def dfs(node):
            if val <= node.val:
                #  Insert leaves directly 
                if not node.left:
                    node.left = TreeNode(val)
                #  Put it on the next floor 
                else:
                    dfs(node.left)
            else:
                if not node.right:
                    node.right = TreeNode(val)
                else:
                    dfs(node.right)
        dfs(root)
        return root

summary

bst Insert common sense