Solution of BST LCA and Invert Binary Tree

Author: Garvit244

200-300q/226.py

@@ -0,0 +1,72 @@
+'''
+	Invert a binary tree.
+
+	Example:
+
+	Input:
+
+	     4
+	   /   \
+	  2     7
+	 / \   / \
+	1   3 6   9
+
+	Output:
+
+	     4
+	   /   \
+	  7     2
+	 / \   / \
+	9   6 3   1
+'''
+
+# 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 invertTree(self, root):
+        """
+        :type root: TreeNode
+        :rtype: TreeNode
+        """
+
+        if not root:
+        	return
+
+        leftTree = self.invertTree(root.left)
+        rightTree = self.invertTree(root.right)
+        root.left = rightTree
+        root.right = leftTree
+        return root
+
+
+# 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 invertTree(self, root):
+        """
+        :type root: TreeNode
+        :rtype: TreeNode
+        """
+        if not root:
+        	return None
+        
+        queue = [root]
+        while queue:
+        	node = queue.pop(0)
+        	node.left, node.right = node.right, node.left
+        	if node.left:
+        		queue.append(node.left)
+        	if node.right:
+        		queue.append(node.right)
+
+        return root

200-300q/235.py

@@ -0,0 +1,53 @@
+'''
+	Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
+
+	According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”
+
+	Given binary search tree:  root = [6,2,8,0,4,7,9,null,null,3,5]
+
+	        _______6______
+	       /              \
+	    ___2__          ___8__
+	   /      \        /      \
+	   0      _4       7       9
+	         /  \
+	         3   5
+
+	Example 1:
+
+	Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
+	Output: 6
+	Explanation: The LCA of nodes 2 and 8 is 6.
+
+	Example 2:
+
+	Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
+	Output: 2
+	Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself 
+	             according to the LCA definition
+'''
+
+# 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 lowestCommonAncestor(self, root, p, q):
+        """
+        :type root: TreeNode
+        :type p: TreeNode
+        :type q: TreeNode
+        :rtype: TreeNode
+        """
+        if not root:
+        	return None
+        
+        if root.val > p.val and root.val > q.val:
+        	return self.lowestCommonAncestor(root.left, p, q)
+        elif root.val < p.val and root.val < q.val:
+        	return self.lowestCommonAncestor(root.right, p, q)
+        else:
+        	return root

README.md

@@ -37,8 +37,10 @@ Python solution of problems from [LeetCode](https://leetcode.com/).
 |239|[Sliding Window Maximum](https://leetcode.com/problems/sliding-window-maximum/)| [Python](./200-300q/239.py)|Hard|
 |238|[Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/)| [Python](./200-300q/238.py)|Medium|
 |236|[Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/)| [Python](./200-300q/236.py)|Medium|
+|235|[Lowest Common Ancestor of a Binary Search Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/)|[Python](./200-300q/235.py)|Easy|
 |234|[Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/)| [Python](./200-300q/234.py)|Easy|
 |230|[Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/)| [Python](./200-300q/230.py)|Medium|
+|226|[Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree)|[Python](./200-300q/226.py)|Easy|
 |215|[Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/)| [Python](./200-300q/215.py)|Medium|
 |210|[Course Schedule II](https://leetcode.com/problems/course-schedule-ii/)| [Python](./200-300q/210.py)|Medium|
 |208|[Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/)| [Python](./200-300q/208.py)|Medium|