tree

Author: Wei Dai

tree/closestBinarySearchTreeValue.py

@@ -0,0 +1,38 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Author: Wei Dai
+
+# ****************
+# Descrption:
+# 270. Closest Binary Search Tree Value
+
+#Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target.
+# ****************
+
+# 思路：
+# BST上二分搜索 把partial optimal和root自己的值进行比较取最优
+
+# ****************
+# Final Solution *
+# ****************
+class Solution(object):
+    def closestValue(self, root, target):
+        """
+        :type root: TreeNode
+        :type target: float
+        :rtype: int
+        """
+        if not root:
+            return -1
+        if not root.left and not root.right:
+            return root.val
+            
+        cur = root.val
+        if target > cur:
+            halfOpt = self.closestValue(root.right, target)
+        else:
+            halfOpt = self.closestValue(root.left, target)
+        cDif, hDif = abs(cur - target), abs(halfOpt - target)
+        res = cur if cDif < hDif else halfOpt
+        return res