Binary Tree Inorder Traversal

Given the root of a binary tree, return the inorder traversal of its nodes' values.

Example 1

Inputroot = [1,null,2,3]

Output[1,3,2]

The inorder traversal visits the root value 1, then the left child of 2, then 2 itself.

Example 2

              1
             / \
            /   \
           2     3
          / \     \
         4   5     8
            / \   /
           6   7 9

Inputroot = [1,2,3,4,5,null,8,null,null,6,7,9]

Output[4,2,6,5,7,1,3,9,8]

Constraints