yo

Author: tech-cow

README.md

@@ -73,7 +73,7 @@ Success is like pregnancy, Everybody congratulates you but nobody knows how many
 |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)|
 |270|[Closest Binary Search Tree Value](https://leetcode.com/problems/closest-binary-search-tree-value/#/description)| [Python [Yu]](./tree/Yu/270.py)| _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)|
-
+|538|[Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree/#/description)| [Python [Yu]](./tree/Yu/538.py) | _O(N)_| _O(1)_  | Easy | |[公瑾讲解](https://youtu.be/YoEPWtXmkD4)|
 
 
 ## Tree Medium

math/453.py

@@ -0,0 +1,46 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Author: Yu Zhou
+# 453. Minimum Moves to Equal Array Elements
+
+
+# 找到当前值和最小值的差，记录一个counter
+class Solution(object):
+    def minMoves(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        count = 0
+        #minu = min(nums)
+        for num in nums:
+            count += num - minu
+        return count
+
+
+
+# 第一次的试验，TLE
+# 思路是每次进行一次sort，然后更改N-1的值
+class Solution(object):
+    def minMoves(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        count = 0
+        if len(nums) == 2:
+            return max(nums) - min(nums)
+
+        while not self.allEqual(nums):
+            nums = sorted(nums)
+            for num in xrange(len(nums)-1):
+                num += 1
+            count += 1
+        return count
+
+
+
+
+    def allEqual(self, nums):
+        return len(set(nums)) <= 1

tree/Yu/109.py

@@ -0,0 +1,46 @@
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def sortedListToBST(self, head):
+        """
+        :type head: ListNode
+        :rtype: TreeNode
+        """
+        # Edge
+        if not head:
+            return None
+        if not head.next:
+            return TreeNode(head.val)
+
+        def findMid(head):
+            slow, fast = head, head
+            pre = None
+            while fast and fast.next:
+                pre = slow
+                slow = slow.next
+                fast = fast.next.next
+            # right here the slow pointer is the mid point
+            # ex: when list is 1,2,3,4.  Slow pointer stops @ 3
+            # ex2: when list is 1,2,3,4,5    Slow pointer stops @ 3 as well
+            pre.next = None
+            return slow
+
+
+        mid = findMid(head)
+        root = TreeNode(mid.val)
+
+        root.left = self.sortedListToBST(head)
+        root.right = self.sortedListToBST(mid.next)
+
+        return root

tree/Yu/538.py

@@ -0,0 +1,30 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def convertBST(self, root):
+        """
+        :type root: TreeNode
+        :rtype: TreeNode
+        """
+       # Input: The root of a Binary Search Tree like this:
+       #        5
+       #      /   \
+       #     2     13
+
+        self.sum = 0
+
+        def dfs(root):
+            if not root:
+                return
+            dfs(root.right)
+            root.val += self.sum
+            self.sum = root.val
+            dfs(root.left)
+
+        dfs(root)
+        return root

tree/Yu/572.py

@@ -1,12 +1,9 @@
-#!/usr/bin/python
-# -*- coding: utf-8 -*-
-
-# Author: Yu Zhou
-# 572. Subtree of Another Tree
-
-# ****************
-# Descrption:
-# ****************
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
 
 class Solution(object):
     def isSubtree(self, s, t):
@@ -15,19 +12,20 @@ def isSubtree(self, s, t):
         :type t: TreeNode
         :rtype: bool
         """
-        #Edge
-        if not s or not t:
-            return False
+        def isMatch(s, t):
+            # 在每层的当前节点，做一套整体的比较
+            # Edge
+            if not s and not t:
+                return True
+            if not s or not t:
+                return False
+            if s.val == t.val:
+                return isMatch(s.left, t.left) and isMatch(s.right, t.right)
+            else:
+                return False
 
-        #Process
-        if self.isMatch(s,t):
+        if isMatch(s, t):
             return True
-
-        #Recusion
+        if not s:
+            return False
         return self.isSubtree(s.left, t) or self.isSubtree(s.right, t)
-
-    def isMatch(self, s, t):
-        if not s or not t:
-            return s == t
-
-        return s.val == t.val and self.isMatch(s.left, t.left) and self.isMatch(s.right, t.right)

tree/Yu/617.py

@@ -0,0 +1,53 @@
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def mergeTrees(self, t1, t2):
+        """
+        :type t1: TreeNode
+        :type t2: TreeNode
+        :rtype: TreeNode
+        """
+
+        # PreOrder Append
+        if not t1 and t2 or not t2 and t1:
+            val1 = t1.val if t1 else 0
+            val2 = t2.val if t2 else 0
+            root = TreeNode(val1+val2)
+        if not t1 and not t2:
+            return root
+
+        # DFS
+        root.left = self.mergeTrees(t1.left, t2.left)
+        root.right = self.mergeTrees(t1.right, t2.right)
+
+
+# Solved
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def mergeTrees(self, t1, t2):
+        """
+        :type t1: TreeNode
+        :type t2: TreeNode
+        :rtype: TreeNode
+        """
+        if t2 and not t1:
+            return t2
+        if t1 and not t2:
+            return t1
+
+        if t1 and t2:
+            root = TreeNode(t1.val + t2.val)
+            root.left = self.mergeTrees(t1.left, t2.left)
+            root.right = self.mergeTrees(t1.right, t2.right)
+            return root