Discord

Implement frontend and backend for Discord message reactions.

Requirements:

interface Reaction {
  emoji: "👍" | "❤️" | "😂";
  count: number;
  hasUserReacted: boolean;
}

interface Message {
  id: string;
  content: string;
  reactions: Reaction[];
}

Frontend Requirements:
1. UI Components
- Reaction display
- Toggle functionality
- Count visualization
- User reaction status

2. State Management
- Track reactions per message
- Handle optimistic updates
- Manage concurrent reactions

Backend Requirements:
1. API Design
```typescript
POST /api/messages/:messageId/reactions
{
  emoji: string;
  action: "add" | "remove";
}

GET /api/messages/:messageId/reactions
Response: Reaction[]

2. Database Schema

CREATE TABLE reactions (
  message_id TEXT,
  user_id TEXT,
  emoji TEXT,
  created_at TIMESTAMP,
  PRIMARY KEY (message_id, user_id, emoji)
);

System Design Considerations:

• Eventually consistent databases
• Concurrent reaction handling
• Race condition prevention
• Real-time updates
• Security measures

Design a matchmaking system for online multiplayer games.

Core Components:

interface Player {
  id: string;
  skillRating: number;
  region: string;
  gamePreferences: GamePreferences;
}

interface MatchRequest {
  player: Player;
  maxWaitTime: number;
  skillRange: number;
}

class MatchmakingSystem {
  // Core functionality
  queuePlayer(request: MatchRequest): void;
  findMatch(player: Player): Player[];
  updateSkillRating(player: Player, newRating: number): void;
}

Requirements:

1. Skill Matching

• ELO/MMR system
• Skill range expansion over time
• Balanced team composition

2. Performance

• Low latency matching
• Handle high concurrent requests
• Regional server support

3. Additional Features

• Party matchmaking
• Role-based matching
• Connection quality consideration
• Anti-abuse measures

Implementation Strategy:

1. Queue Management

• Priority queue based on wait time
• Skill range bands
• Regional partitioning

2. Matching Algorithm

• Initial strict matching
• Gradual range expansion
• Fairness considerations

3. System Architecture

• Distributed queues
• Real-time updates
• Match quality monitoring