var uniquePaths = function (m, n) {
  const memo = [];
  for (let i = 0; i < n; i++) {
    memo.push([]);
  }
  for (let row = 0; row < n; row++) {
    memo[row][0] = 1;
  }

  for (let col = 0; col < m; col++) {
    memo[0][col] = 1;
  }

  for (let row = 1; row < n; row++) {
    for (let col = 1; col < m; col++) {
      memo[row][col] = memo[row - 1][col] + memo[row][col - 1];
    }
  }

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