1
var uniquePaths = function (m, n) {
2
  let count = Array(m);
3
  for (let i = 0; i < m; i++) count[i] = Array(n);
4
  for (let i = 0; i < m; i++) {
5
    for (let j = 0; j < n; j++) {
6
      if (i == 0 || j == 0) count[i][j] = 1;
7
      else count[i][j] = count[i][j - 1] + count[i - 1][j];
8
    }
9
  }
10
  return count[m - 1][n - 1];
11
};