shortpathbinarymatrix.js

function shortestPathBinaryMatrix(grid) {
  const directions = [
    [1, 0],
    [-1, 0],
    [0, 1],
    [0, -1],
    [1, 1],
    [1, -1],
    [-1, 1],
    [-1, -1],
  ];

  if (grid[0][0] === 1) {
    return -1;
  }

  const N = grid.length;
  const queue = [[0, 0, 1]]; // [row, col, path]

  while (queue.length) {
    const [row, col, path] = queue.shift();

    if (row === N - 1 && col === N - 1) {
      return path; // reached destination
    }

    for (const [dx, dy] of directions) {
      // traverse adjacents
      let x = row + dx;
      let y = col + dy;

      // if invalid, continue
      if (x < 0 || x >= N) continue;
      if (y < 0 || y >= N) continue;
      if (grid[x][y] !== 0) continue;

      queue.push([x, y, path + 1]); // add new path to queue
      grid[x][y] = 1; // mark visited
    }
  }

  return -1;
}