python leetcode 653

python-leetcode/README.md

@@ -32,6 +32,7 @@
 18. [对称二叉树](./solution/tree/leetcode_101_.py)
 19. [二叉搜索树节点最小距离](./solution/tree/leetcode_783_.py)
 20. [二叉树的坡度](./solution/tree/leetcode_563_.py)
+21. [ 两数之和 IV - 输入 BST](./solution/tree/leetcode_653_.py)
 
 
 

python-leetcode/solution/tree/leetcode_653_.py

+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# coding=utf-8
+"""
+653. 两数之和 IV - 输入 BST
+"""
+from solution import TreeNode
+
+
+class Solution:
+    def findTarget(self, root: TreeNode, k: int) -> bool:
+        res = []
+
+        def helper(root: TreeNode):
+            nonlocal res
+            if root:
+                helper(root.left)
+                res.append(root.val)
+                helper(root.right)
+
+        helper(root)
+        start = 0
+        end = len(res) - 1
+        while start < end:
+            if (res[start] + res[end]) > k:
+                end = end - 1
+            elif (res[start] + res[end]) < k:
+                start = start + 1
+            else:
+                return True
+        return False