moderate

JavaScript Queues - Moderate Level

This section covers moderate difficulty queue problems from LeetCode, implemented using modern ES6+ JavaScript features.

Problems

1. Design Circular Queue
2. Implement Queue using Stacks
3. Sliding Window Maximum

Approaches

Each problem is solved using multiple approaches showcasing different JavaScript features and patterns:

Problem 1: Design Circular Queue

• Approach 1: Basic Circular Queue Implementation
• Approach 2: Circular Queue Implementation using Linked List
• Approach 3: Circular Queue Implementation using Map
• Approach 4: Functional Circular Queue Implementation
• Approach 5: Circular Queue with Custom Iterator
• Approach 6: Generator-based Circular Queue Implementation with Step-by-Step Visualization

Problem 2: Implement Queue using Stacks

• Approach 1: Two-Stack Implementation (Enqueue Heavy)
• Approach 2: Two-Stack Implementation (Dequeue Heavy)
• Approach 3: Functional Implementation using Factory Function
• Approach 4: Implementation using Map for Element Tracking
• Approach 5: Queue Implementation with Custom Iterator
• Approach 6: Generator-based Queue Implementation with Step-by-Step Visualization

Problem 3: Sliding Window Maximum

• Approach 1: Brute Force Solution
• Approach 2: Deque (Double-ended Queue) Solution
• Approach 3: Dynamic Programming Solution
• Approach 4: Priority Queue (Max Heap) Solution
• Approach 5: Functional Programming Solution
• Approach 6: Generator-based Solution with Step-by-Step Visualization

Key JavaScript Features Used

• ES6+ syntax (arrow functions, destructuring, spread operator)
• Modern data structures (Map, Set)
• Functional programming patterns
• Factory functions
• Custom iterators with Symbol.iterator
• Generator functions for step-by-step visualization
• Performance testing utilities
• Comprehensive documentation with time/space complexity analysis

Usage

Each implementation file can be run independently to see the implementation in action:

node answer1.js
node answer2.js
node answer3.js

Performance Comparison

All implementations include performance testing utilities to compare different approaches:

// Performance comparison utility
const performanceTest = (func, name, nums, k) => {
  const start = performance.now();
  func([...nums], k);
  const end = performance.now();
  console.log(`${name}: ${end - start}ms for array of size ${nums.length} with window size ${k}`);
};

Source

Problems from LeetCode Hard:

• https://leetcode.com/problems/design-circular-queue/
• https://leetcode.com/problems/implement-queue-using-stacks/
• https://leetcode.com/problems/sliding-window-maximum/