leetcode-mid-Linked list-94 Binary Tree Inorder Traversal

mycode  95%

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

class Solution(object):
    def inorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        if not root:
            return []
        self.res = []
        def inorder(root):
            if not root:
                return   
            inorder(root.left)
            self.res.append(root.val)
            inorder(root.right)
        inorder(root)
        return self.res

参考：

重点是递归的理解：

大：先得到左子树的list，再加上root的val，再加上右子树的list

小：迭代，最小的tree也应该符合上述规则

class Solution(object):
    def inorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        if root == None:
            return []
        
        left = self.inorderTraversal(root.left)
        right = self.inorderTraversal(root.right)
        left.append(root.val)
        left.extend(right)
        return left