You're building the classic Snake game. The board is a 20x20 grid where the snake moves, food appears randomly, and walls kill the snake. How should you represent the game board so that collision checks are fast?

Code

class Position {
  constructor(public row: number, public col: number) {}
  equals(other: Position): boolean {
    return this.row === other.row && this.col === other.col
  }
  toString(): string { return `${this.row},${this.col}` }
}

class Board {
  private width: number
  private height: number
  private snakePositions: Set<string>  // O(1) collision check
  private foodPosition: Position | null

  isValidPosition(pos: Position): boolean {
    return pos.row >= 0 && pos.row < this.height
        && pos.col >= 0 && pos.col < this.width
  }

  hasSnakeAt(pos: Position): boolean {
    return this.snakePositions.has(pos.toString())
  }
}

Question

What's the best way to represent the game board?

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Board Representation

Efficient Collision Detection

Code

class Position {
  constructor(public row: number, public col: number) {}
  equals(other: Position): boolean {
    return this.row === other.row && this.col === other.col
  }
  toString(): string { return `${this.row},${this.col}` }
}

class Board {
  private width: number
  private height: number
  private snakePositions: Set<string>  // O(1) collision check
  private foodPosition: Position | null

  isValidPosition(pos: Position): boolean {
    return pos.row >= 0 && pos.row < this.height
        && pos.col >= 0 && pos.col < this.width
  }

  hasSnakeAt(pos: Position): boolean {
    return this.snakePositions.has(pos.toString())
  }
}

Question

What's the best way to represent the game board?