[프로그래머스 Level 2] 게임 맵 최단거리

function solution(maps) {
    const m = maps.length;
    const n = maps[0].length;
 
    const dx = [0, 1, 0, -1];
    const dy = [1, 0, -1, 0];
 
    function bfs(matrix, start_x = 0, start_y = 0){
        const q = [ [start_x, start_y] ];
        const visited = Array.from({ length: m }).map(_ => Array.from({ length: n }).fill(0));  // 중복 방문 방지
 
        while(q.length){
            const [x, y] = q.shift();
 
            if(visited[y][x] === 0){
                if(x === n-1 && y === m-1)  return matrix[y][x];
 
                visited[y][x] = 1;
 
                dx.forEach((_, i) => {
                    const nx = Math.min(Math.max(x + dx[i], 0), n-1);
                    const ny = Math.min(Math.max(y + dy[i], 0), m-1);
 
                    if(matrix[ny][nx] && !visited[ny][nx]){
                        matrix[ny][nx] = matrix[y][x] + 1;
                        q.push([nx, ny]);
                    }
                });
            }
        }
        return -1;
    }
 
    return bfs(maps);
}