Leetcode Binary Tree Preorder, inorder, postorder Traversal (python)

题目

https://leetcode.com/problems/binary-tree-preorder-traversal/
https://leetcode.com/problems/binary-tree-inorder-traversal/submissions/
https://leetcode.com/problems/binary-tree-postorder-traversal/submissions/

解析：

一律用dfs来写，只需要改变访问节点的位置即可

preorder

class Solution:def postorderTraversal(self, root: TreeNode) -> List[int]:def dfs(node):if not node:returndfs(node.left)dfs(node.right)ans.append(node.val)ans = []dfs(root)return ans

inorder

class Solution:def inorderTraversal(self, root: TreeNode) -> List[int]:def dfs(node):if not node:returndfs(node.left)ans.append(node.val)dfs(node.right)ans = []dfs(root)return ans

postorder

class Solution:def postorderTraversal(self, root: TreeNode) -> List[int]:def dfs(node):if not node:returndfs(node.left)dfs(node.right)ans.append(node.val)ans = []dfs(root)return ans