Reddit

Implement a hit counter for tracking requests in last 5 minutes.

Class Methods:

class HitCounter {
    hit(timestamp: number): void
    getHits(timestamp: number): number
}

Requirements:

• Track hits within 5-minute window
• Optimize for efficient retrieval
• Handle timestamp ordering
• Thread-safe implementation

Example: hit(10) hit(9) getHits(100) → 2 hit(201) getHits(400) → 2

Implement word transformation with shortest path finding.

Part 1: Basic Transformation Check if transformation possible from beginWord to endWord.

Part 2: Shortest Path Find length of shortest transformation sequence.

Example: beginWord = "hit" endWord = "cog" wordList = ["hot","dot","dog","lot","log","cog"] Output: 5 (hit→hot→dot→dog→cog)

Part 3: All Shortest Paths Find all possible shortest transformation sequences.