JAVA算法练习题day28

36.二叉树的中序遍历

开始用python了

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):def inorderTraversal(self, root):res = []""":type root: Optional[TreeNode]:rtype: List[int]"""#Python 的dfs是嵌套函数，可以直接访问外部的res列表（不需要像 C++/Java 那样作为参数传递）。def dfs(node):if node is None:return dfs(node.left)res.append(node.val)dfs(node.right)dfs(root)return res

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):def inorderTraversal(self, root):""":type root: Optional[TreeNode]:rtype: List[int]"""res = []stack = [] #用栈模拟递归过程current = root #当前节点指针，初始时指向根节点while current is not None or stack:if current is not None:stack.append(current)current = current.leftelse:current = stack.pop()res.append(current.val)current = current.rightreturn res