res.js

/**
 * @param {number[][]} obstacleGrid
 * @return {number}
 */
var uniquePathsWithObstacles = function(obstacleGrid) {
  const n = obstacleGrid.length;
  if (!n) return 0;
  const m = obstacleGrid[0].length;
  if (!m) return 0;

  for (let i = 0; i < n; i++) {
    for (let j = 0; j < m; j++) {
      if (i === 0 && j === 0) {
        obstacleGrid[i][j] = obstacleGrid[i][j] ? 0 : 1;
      } else if (i == 0) {
        obstacleGrid[i][j] = obstacleGrid[i][j] || !obstacleGrid[i][j-1] ? 0 : 1;
      } else if (j == 0) {
        obstacleGrid[i][j] = obstacleGrid[i][j] || !obstacleGrid[i-1][j] ? 0 : 1;
      } else {
        obstacleGrid[i][j] = obstacleGrid[i][j] ? 0 : obstacleGrid[i-1][j] + obstacleGrid[i][j-1];
      }
    }
  }

  return obstacleGrid[n-1][m-1];
};