62. Unique Paths

Description:

Solution:

row = [1] * n  => The bottom row: [1, 1, 1, 1, 1, 1, 1]

We start from (n-2) with reverse order. When we complete the second row[7, 6, 5, 4, 3, 2, 1], we update this newRow as row. 

 

Time Complexity: O(n*m)

Space Complexity: O(n)