这个题的关键，就是用一个deque 来纪录蛇🐍的身体，然后用一个hash table 来判断蛇会不会撞到自己的身体然后死掉

C++ 代码

class SnakeGame {
private:
    int width;
    int height;
    int foodIdx;
    vector<pair<int, int>> food;
    unordered_set<int> map;
    deque<pair<int, int>> snake;

public:
    /** Initialize your data structure here.
        @param width - screen width
        @param height - screen height 
        @param food - A list of food positions
        E.g food = [[1,1], [1,0]] means the first food is positioned at [1,1], the second is at [1,0]. */
    SnakeGame(int width, int height, vector<pair<int, int>> food) {
        this->width = width;
        this->height = height;
        foodIdx = 0;

        this->food = food;

        map.insert(0);
        snake.push_back(pair<int, int>(0, 0));        
    }

    /** Moves the snake.
        @param direction - 'U' = Up, 'L' = Left, 'R' = Right, 'D' = Down 
        @return The game's score after the move. Return -1 if game over. 
        Game over when snake crosses the screen boundary or bites its body. */
    int move(string direction) {
        int dx = 0;
        int dy = 0;

        if (direction == "U"){
            dx = -1;
        }
        else if (direction == "D"){
            dx = 1;
        }
        else if (direction == "L"){
            dy = -1;
        }
        else{
            dy = 1;
        }

        int x = snake.back().first + dx;
        int y = snake.back().second + dy;

        if (x>=0 && x < height && y >= 0 && y < width){
            snake.push_back(pair<int, int>(x, y));

            if (foodIdx < food.size() && pair<int, int>(x, y) == food[foodIdx]){
                foodIdx++;
            }
            else{
                map.erase(snake.front().first*width + snake.front().second);   
                snake.pop_front();
            }

            if (map.count(x*width + y)){
                return -1;
            }
            else{
                map.insert(x*width + y);
            }

            return foodIdx;
        }
        else{
            return -1;
        }        
    }
};