Solution.ts

class SnakeGame {
    private m: number;
    private n: number;
    private food: number[][];
    private score: number;
    private idx: number;
    private q: number[];
    private vis: Set<number>;

    constructor(width: number, height: number, food: number[][]) {
        this.m = height;
        this.n = width;
        this.food = food;
        this.score = 0;
        this.idx = 0;
        this.q = [0];
        this.vis = new Set([0]);
    }

    move(direction: string): number {
        const p = this.q[0];
        const i = Math.floor(p / this.n);
        const j = p % this.n;
        let x = i;
        let y = j;
        if (direction === 'U') {
            --x;
        } else if (direction === 'D') {
            ++x;
        } else if (direction === 'L') {
            --y;
        } else {
            ++y;
        }
        if (x < 0 || x >= this.m || y < 0 || y >= this.n) {
            return -1;
        }
        if (
            this.idx < this.food.length &&
            x === this.food[this.idx][0] &&
            y === this.food[this.idx][1]
        ) {
            ++this.score;
            ++this.idx;
        } else {
            const t = this.q.pop()!;
            this.vis.delete(t);
        }
        const cur = x * this.n + y;
        if (this.vis.has(cur)) {
            return -1;
        }
        this.q.unshift(cur);
        this.vis.add(cur);
        return this.score;
    }
}

/**
 * Your SnakeGame object will be instantiated and called as such:
 * var obj = new SnakeGame(width, height, food)
 * var param_1 = obj.move(direction)
 */