Practice/Apple/Leetcode 353. Design Snake Game

Leetcode 353. Design Snake Game

CodingMust

Problem

Design and implement a classic Snake game that operates on an m × n grid. The snake starts at position (0, 0) with an initial length of 1 cell. Food items appear at predetermined locations on the grid in a specific sequence. When the snake's head reaches a food item, the snake consumes it, grows by one segment, and the player's score increases by 1.

Your implementation should support a move operation that advances the snake one cell in a given direction ("U" for up, "D" for down, "L" for left, "R" for right). The game ends when:

• The snake moves outside the grid boundaries (hitting a wall)
• The snake's head collides with any part of its own body

When the game ends, return -1. Otherwise, return the current score (number of food items eaten).

Requirements

1. Implement a SnakeGame class with a constructor that accepts grid dimensions (width and height) and a list of food positions
2. Implement a move(direction) method that moves the snake one step in the specified direction
3. Track the snake's body position efficiently to handle collision detection
4. Manage food consumption: when the snake's head reaches the next food position in the sequence, it grows and the score increases
5. Return the current score after each valid move, or -1 if the game ends

Constraints

• 1 ≤ width, height ≤ 10⁴
• 0 ≤ food.length ≤ 50
• food[i].length == 2
• 0 ≤ food[i][0] < height
• 0 ≤ food[i][1] < width
• direction is one of: "U", "D", "L", "R"
• At most 10⁴ calls will be made to move
• Food positions are given in the order they will appear

Examples

Example 1:

` Grid: 3 rows × 2 columns Food: [[1,2], [0,1]]

Operations: move("R") → score = 0, snake at [0,1] move("D") → score = 0, snake at [1,1] move("R") → score = 1, snake at [1,2], ate food, length = 2 move("U") → score = 1, snake at [0,2] move("L") → score = 2, snake at [0,1], ate food, length = 3 move("U") → score = -1, game over (hit wall) `

Example 2:

` Grid: 3 rows × 3 columns Food: [[2,0]]

Operations: move("D") → score = 0, snake at [1,0] move("D") → score = 0, snake at [2,0], ate food, length = 2 move("R") → score = 1, snake at [2,1] move("U") → score = -1, game over (hit own body) `