题解 | #二叉树的中序遍历#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型一维数组
#
class Solution:
    def inorderTraversal(self , root: TreeNode) -> List[int]:
        # write code here
        
        if not root: return []
        
        # 迭代
        stack = []
        res = []
        cur = root
        while stack or cur:
            while cur:
                stack.append(cur)
                cur = cur.left
            
            node = stack.pop() # 栈顶元素出栈
            res.append(node.val) # 栈顶元素加入输出结果
            cur = node.right # 当前元素为栈顶元素的右节点
        
        return res