Leetcode Binary Tree Preorder, inorder, postorder Traversal

题目解析：

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: return dfs(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: return dfs(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: return dfs(node.left) dfs(node.right) ans.append(node.val) ans = [] dfs(root) return ans