Freaks City

Binary trees are hierarchical data structures with nodes containing up to two children. Common types include full binary trees where every node has either zero or two children, and complete binary trees where all levels are fully filled except possibly the last level. Storage methods include linked storage using node references and sequential s ...

In a tree-structured neighborhood where the root represents the delivery station, a courier must visit all requested delivery nodes at least once. The goal is to compute, after each new delivery request, the shortest total distance required to deliver all orders so far—without needing to return to the root. The key insight is that traversing al ...

Lowest Common Ancestor in a BST (LeetCode 235) Given a BST and two nodes p and q, find their lowest common ancestor (LCA). The BST property allows an efficient traversal from root down: the LCA is the first node whose value lies between p->val and q->val (inclusive). Because the tree is ordered, moving left/right narrows down the range un ...

Trimming a Binary Search TreeGiven a Binary Search Tree (BST) and a valid range [low, high], the task is to trim the tree so that all node values fall within this inclusive range. The structure of the resulting tree should maintain BST properties.A common mistake is to simply return null when encountering a node outside the range:class Solution ...

Given an integer, determine if it is a palindrome. The straightforward apprroach is to treat the input as a string and check if it reads the same forwards and backwards, which can be done in O(n) time where n is the length of the string. A more efficient approach uses polynomial hashing with O(n) time complexity. We'll implement both forward an ...

590. N-ary Tree Postorder Traversal Approach: Right-to-left, then root-to-left. Use a stack with a visited set to track processed nodes. class Node: def __init__(self, val=None, children=None): self.val = val self.children = children def postorder(root): if not root: return [] stack = [root] result = [] ...

Given a family tree, the task is to output the smallest generation (youngest descendants) and list all members belonging to that generation. Input Format: The first line contains an integer N (1 ≤ N ≤ 100,000), the total number of family members, each assigned a unique ID from 1 to N. The second line provides N integers where the i-th integer r ...

Given a binary tree, we need to install cameras on its nodes. Each camera can monitor its parent, itself, and its immediate children. The goal is to determine the minimum number of cameras reuqired to cover the entire tree. Problem Constraints Number of nodes ranges from 1 to 1000. Node values are irrelevant (typically 0). Core Strategy The o ...

Core Traversal DefinitionsPre-order: Process the root node, traverse the left subtree, then traverse the right subtree.In-order: Traverse the left subtree, process the root node, then traverse the right subtree.Post-order: Traverse the left subtree, traverse the right subtree, then process the root node.Building from Pre-order and In-order Sequ ...

Stack and Queue Fundamentals Stacks and queues share the trait that insertion and deletion occur solely at their endpoints. Typical stack storage models are sequential arrays and linked lists. A stack exhibits last-in-first-out behavior. Linked lists lack random access; elemants must be traversed sequentially. Linked representation simplifies ...