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235. Lowest Common Ancestor of a Binary Search Tree class Solution: def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode': if p.val <= root.val <= q.val or q.val <= root.val <= p.val: return root if p.val < root.val and q.val < root.val and root.left: return self.lowestCommonAncestor(root.left, p, q) elif root.right: return self.lowestCommonAncestor(root.right, p, q) 102. Binary Tree Level Order Traversal class Solution: def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]: if not root: return [] q = deque() q.append(root) ans = [] while(q): level_size = len(q) level = [] for i in range(level_size): el = q.popleft() level.append(el.val) if el.left: q.append(el.left) if el.right: q.append(el.right) ans.append(level) return ans 98. Validate Binary Search Tree class Solution: def isValidBST(self, root: Optional[TreeNode]) -> bool: def helper(root, low, high): if not root: return True elif low < root.val < high: return helper(root.left, low, root.val) and helper(root.right, root.val, high) else: return False return helper(root, float('-inf'), float('inf'))

HDFS and MapReduce can be confusing at times. Let’s break down the entire process step-by-step with a concrete example. The example I’m going to use is calculating the average movie rating per genre from a CSV file. First, we have to upload the CSV file into HDFS, and then we will run a MapReduce job to compute the average ratings. We assume: Data format: genre,rating Goal: average rating per genre ...

In this blog, we are going to explore the world of regular expressions Regular expressions are used for parsing and validating strings especially in applications of Natural Language Processing 1. Literals Pattern Meaning cat Match all occurences of “cat” anywhere inside the text 2. Character Classes Pattern Meaning [abc] a or b or c [a-zA-Z0-9] Any lowercase or uppercase or digit [^a-z] Anything except lowercase 3. Quantifiers Pattern Meaning * 0 or more occurence + 1 or more occurence ? 0 or 1 occurence {n} Exactly n occurences {n,} n or more occurences {n, m} Between n and m occurences 4. Anchors Pattern Meaning ^ Start of a string $ End of a string \b Word boundary \B Non-boundary 5. Grouping Pattern Meaning (abc) Grouping (useful for extraction) 6. Alternation Pattern Meaning a|b Alternation (a or b) 7. Escape Sequences Pattern Meaning \. When you want to use a “.” or any other symbol in literal sense use “\” as an escape sequence 8. Predefined Classes Pattern Meaning \d digit(0-9) \D non-digit \w word char (letters, digits) \W non-word char \s whitespace \S non-whitespace Python re module Search ( Find first occurence of the pattern in the text ) Find first word starting with capital letter ...

The 2-link manipulator is a fundamental robotics system that is used by robot enthusiasts to understand the principles of kinematics. A 2-link manipulator consists of two rigid links connected by revolute joints, allowing for planar motion. In this post, we will explore the forward and inverse kinematics of a 2-link manipulator. Forward kinematics - Given joint parameters, what is the position of the end-effector Inverse kinematics - Given the position of the end-effector, what are the joint parameters ...

DES is a symmetric-key block cipher that follows the Fiestal Cipher structure. The steps involved in encryption are: Apply an initial permutation to the 64-bit input block using a permutation matrix Similar to the Fiestal Cipher structure, split the 64 bit output after permutation into 2 halves \(L_0\) (32 bits) and \(R_0\) (32 bits) Compute F(\(R_0\), \(k_0\)) using expansion, XOR, S-boxes, and permutation Set \(L_1\) = \(R_0\) and \(R_1\) = \(L_0\) XOR F(\(R_0\), \(k_0\)) Now, this concludes the first round. Now, do steps 3-4 15 more times After round 16, perform a 32-bit swap like in Fiestal Cipher structure Undo the initial permutation to get the cipher text ...

This blog will help you build your own blog site using Hugo with PaperMod theme and deploy it in github pages for $0 1. What is Hugo ? Hugo is a fast static site generator. It converts Markdown files into a full HTML, CSS, and Javascript site using a theme. Advantages: Extremely fast serving after deployment Intuitive folder based structure Great for blogs and portfolios Works effortlessly with Github Pages 2. Prerequisites Make sure git is installed. git will help you deploy your site to Github pages as well as add themes to your hugo site If you don’t have git, please refer to: Git Installation ...

My first Hello World post.