270

Author: tech-cow

README.md

@@ -70,7 +70,7 @@ Success is like pregnancy, Everybody congratulates you but nobody knows how many
 |-----|-------| -------- | ---- | ------|------------|---|-----|
 |110|[Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/#/description)| [Python [Yu]](./tree/Yu/110_isBalanced.py) | _O(N)_| _O(h)_  | Easy | ||
 |112|[Path Sum](https://leetcode.com/problems/path-sum/#/description)| [Python [Yu]](./tree/Yu/112_hasPathSum.py) | _O(N)_| _O(h)_  | Easy | |[中文讲解](https://www.youtube.com/watch?v=LgtcGjIuE18&feature=youtu.be)|
-|404|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/#/description)| [Python [Yu]](./tree/Yu/404_sum_of_Left_Leaves.py) | _O(N)_| _O(h)_  | Easy | ||
+
 
 
 
@@ -79,7 +79,7 @@ Success is like pregnancy, Everybody congratulates you but nobody knows how many
 |  #  | Title | Solution | Time | Space | Difficulty |Tag| Note|
 |-----|-------| -------- | ---- | ------|------------|---|-----|
 |100|[Same Tree](https://leetcode.com/problems/same-tree/)| [Python [Yu]](./tree/Yu/100_isSameTree.py) <br> [Python [Sheng]](./tree/YeSheng/100.Same_Tree.py) | _O(N)_| _O(1)_  | Easy ||[EAFP vs. LBYL](https://github.com/ictar/python-doc/blob/master/Others/%E5%AE%9E%E7%94%A8Python%EF%BC%9AEAFP%20VS.%20LBYL.md)|
-|101|[Symmetric Tree](https://leetcode.com/problems/symmetric-tree/#/description)| [Python [Yu]](./tree/Yu/101_symmetricTree.py) <br> [Python [Sheng]](./tree/YeSheng/101.Symmetric_Tree.py) | _O(N)_| _O(1)_  | Easy ||[Editorial Solution](https://leetcode.com/articles/symmetric-tree/)|
+
 |111|[Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/#/description)| [Python [Yu]](https://github.com/yuzhoujr/LeetCode/blob/master/tree/Yu/111_minDepth.py) <br> [Python [Sheng]](https://github.com/yuzhoujr/LeetCode/blob/master/tree/YeSheng/111.Minimum_Depth_of_Binary_Tree.py) | _O(N)_| _O(1)_  | Easy |||
 |104|[Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)| [Python](./tree/Yu/104_maxDepth.py) | _O(N)_| _O(1)_  | Easy | ||
 |235|[Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/#/description)| [Python](./tree/Yu/235_lca_bst.py) | _O(N)_| _O(1)_  | Easy | ||
@@ -93,7 +93,13 @@ Success is like pregnancy, Everybody congratulates you but nobody knows how many
 |543|[Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/#/description)| [Python [Yu]](./tree/Yu/543.py) | _O(N)_| _O(h)_  | Easy | |[公瑾讲解](https://www.youtube.com/watch?v=0VnOfu2pYTo)|
 |501|[Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree/#/description)| [Python [Yu]](./tree/Yu/501.py) | _O(N)_| _O(N)_  | Easy | |[公瑾讲解](https://youtu.be/v4F4x_uwMb8)|
 |572|[Subtree of Another Tree](https://leetcode.com/problems/subtree-of-another-tree/#/description)| [Python [Yu]](./tree/Yu/572.py) | _O(S*T)_| _O(1)_  | Easy | |[公瑾讲解](https://youtu.be/v4F4x_uwMb8)|
-|437|[Path Sum III](https://leetcode.com/problems/path-sum-iii/#/description)| [Python [Yu]](./tree/Yu/437.py) | _O(N^2)_| _O(1)_  | Easy | |[公瑾讲解](https://youtu.be/NTyOEYYyv-o)|
+|437|[Path Sum III](https://leetcode.com/problems/path-sum-iii/#/description)| [Python [Yu]](./tree/Yu/437.py) | _O(N^2)_| _O(1)_  | Easy | ||
+|404|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/#/description)| [Python [Yu]](./tree/Yu/404_sum_of_Left_Leaves.py) | _O(N)_| _O(1)_  | Easy |
+|[公瑾讲解](https://youtu.be/pH-KxPcBF_4)|
+|101|[Symmetric Tree](https://leetcode.com/problems/symmetric-tree/#/description)| [Python [Yu]](./tree/Yu/101_symmetricTree.py)| _O(N)_| _O(1)_  | Easy ||[公瑾讲解](https://youtu.be/3Gl4F29LVpQ)|
+|270|[Closest Binary Search Tree Value](https://leetcode.com/problems/closest-binary-search-tree-value/#/description)| [Python [Yu]](./tree/Yu/270)| _O(N)_| _O(1)_  | Easy ||[公瑾讲解](https://youtu.be/RwvQyKJxHZk)|
+
+
 
 
 |563|[Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt/#/description)| [Python [Yu]](./tree/Yu/563.py) | _O(N)_| _O(1)_  | Easy | |[公瑾讲解](https://youtu.be/47FQVP4ynk0)|

tree/Yu/270.py

@@ -0,0 +1,32 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Author: Yu Zhou
+# 270. Closest Binary Search Tree Value
+
+# ****************
+# Descrption:
+# ****************
+
+class Solution(object):
+    def closestValue(self, root, target):
+
+        #Edge Case:
+        if not root:
+            return 0
+
+        self.res = root.val
+        #Process
+        def dfs(root, target):
+            if not root:
+                return 0
+            if abs(target - self.res) > abs(target - root.val):
+                self.res = root.val
+            if target > root.val:
+                dfs(root.right, target)
+            else:
+                dfs(root.left, target)
+
+        # Recursion
+        dfs(root, target)
+        return self.res

tree/Yu/404_sum_of_Left_Leaves.py

@@ -4,13 +4,19 @@ def sumOfLeftLeaves(self, root):
         :type root: TreeNode
         :rtype: int
         """
+        # Edge
         if not root:
             return 0
+        # Process
+        self.count = 0
+        def dfs(root):
+            if not root:
+                return 0
+            if root.left and not root.left.left and not root.left.right:
+                self.count += root.left.val
+            # Recursion
+            dfs(root.left)
+            dfs(root.right)
 
-        if root.left and root.left.left == None and root.left.right == None:
-            return root.left.val + self.sumOfLeftLeaves(root.right)
-
-        left = self.sumOfLeftLeaves(root.left)
-        right = self.sumOfLeftLeaves(root.right)
-
-        return left + right
+        dfs(root)
+        return self.count