[Leetcode] 94. Binary Tree Inorder Traversal

문제 바로가기

Time Complexity: $O(n)$
Space Complexity: $O(n)$

# 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 inorderTraversal(self, root: TreeNode) -> List[int]:
        def traversal(node: TreeNode, trav: List[int]) -> None:
            # node not exist
            if not node:
                return
            # inorder: left child -> parent -> right child
            if node.left:
                traversal(node.left, trav)
            trav.append(node.val)
            if node.right:
                traversal(node.right, trav)
                
        res = list()
        traversal(root, res)
        return res