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Given an integer array nums and an integer k, a sliding window of size k traverses the array from left to right. Only the k numbers within the window are visible at any step, and the window shifts right by one position after each move. The task is to return the maximum element inside the window for every valid posiiton. Example 1 Input: nums = ...

Collections Module Overview The collections module provides specialized container alternatives to Python's built-in containers like list, dict, set, and tuple. Key components include: namedtuple: Creates tuple subclasses with named fields deque: Double-ended queue for efficient appends/pops Counter: Dictionary subclass for counting hashable ob ...

A monotonic queue is a specialized data structure that maintains elements in either strictly increasing or decreasing order. Unlike standard queues, a monotonic queue allows operations at both the front and rear, functioning as a double-ended queue (deque) where elements are kept in sorted order. The Core Principle The fundamental insight behin ...

Evaluating Reverse Polish Notation (LeetCode 150) Reverse Polish Notation (RPN), also known as postfix expression, places operators after thier operands. For example, the infix expression (1 + 2) * (3 + 4) becomes 1 2 + 3 4 + * in RPN. This notation eliminates ambiguity and parenthetical grouping, making it ideal for stack-based evaluation. The ...

Stack Imagine organizing a closet by placing winter clothes first, then summer clothes on top. When summer arrives, you grab the summer clothes first from the top without disturbing the items below. A stack is a container that allows storing, accessing, and removing elements exclusively from one end called the top. This constraint means the ele ...

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its zigzag level order traversal as: [ [3], [20,9], [15,7] ] Appr ...

DataSource Context Holder Implementation Based on Deque public class DataSourceContextManager { // Using ThreadLocal<Deque> to support nested data sources private static final ThreadLocal<Deque<DataSourceEnum>> CONTEXT_HOLDER = ThreadLocal.withInitial(ArrayDeque::new); /** * Push data source type ...

Problem A - Sum of Two Smallest Numbers Statement: Given three integers, output the sum of the two smallest values. Solution: Subtract the maximum value from the total sum. int a, b, c; cin >> a >> b >> c; cout << a + b + c - max({a, b, c}) << endl; Problem B - Finding the Longest Even Prefix Statement: A string i ...

The essence of a container adapter lies in the principle of reuse. Instead of implementing storage structures from scratch, these adapters leverage existing containers to handle data storage while exposing only the interfaces relevant to their specific access patterns. This adapter pattern represents a fundamental design philosophy in software ...

Evaluating Reverse Polish Notation Reverse Polish Notation (RPN) eliminates the need for parentheses by placing operators after their operands. A stack-based approach efficiently processes tokens in a single pass. class Solution { public: int evalRPN(vector<string>& expr) { stack<int> eval_stack; for (const a ...