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export default snakesAndLadders;function snakesAndLadders(board: number[][]): number {    const n = board.length;    const vis = new Set<number>([1]);    const queue = [[1, 0]];    while (queue.length) {        const p = queue.shift() as [number, number];        for (let i = 1; i <= 6; ++i) {            let nxt = p[0] + i;            if (nxt > n * n) { // 超出边界                break;            }            const rc = id2rc(nxt, n); // 得到下一步的行列            if (board[rc[0]][rc[1]] > 0) { // 存在蛇或梯子                nxt = board[rc[0]][rc[1]];            }            if (nxt === n * n) { // 到达终点                return p[1] + 1;            }            if (!vis.has(nxt)) {                vis.add(nxt);                queue.push([nxt, p[1] + 1]); // 扩展新状态            }        }    }    return -1;}function id2rc(id: number, n: number) {    const r = Math.floor((id - 1) / n);    let c = (id - 1) % n;    if (r % 2 === 1) {        c = n - 1 - c;    }    return [n - 1 - r, c];}