LeetCode 94. Binary Tree Inorder Traversal 时间复杂度(O(n))

时间复杂度(O(n))，思想：中序遍历

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    r = []

    def mid_node(self, root: TreeNode):
        if root == None: return
        self.mid_node(root.left)
        self.r.append(root.val)
        self.mid_node(root.right)

    def inorderTraversal(self, root: TreeNode) -> [int]:
        self.r = []
        self.mid_node(root)
        return self.r