Unique Paths in a Grid

solution_unique_paths_grid.py

import copy

#Unique Paths in a Grid
#only X,Y+1 and X+1,y movements allowed
# -1 is obstacle

class Solution:
    def get_number_of_possible_paths(self, list_of_rows):
        potencial_list = copy.copy(list_of_rows)
        lo = list_of_rows

        idx_len = len(lo)
        jdx_len = len(lo[idx_len-1])

        for idx,line in enumerate(list_of_rows):
            for jdx,obj in enumerate(line):
                if(list_of_rows[idx][jdx] != -1): #not an obstacle
                    counter = 1 if (idx == 0 and jdx == 0) else 0
                    if(jdx != 0 and list_of_rows[idx][jdx-1] != -1):
                        counter += lo[idx][jdx-1]
                    if(idx != 0 and list_of_rows[idx-1][jdx] != -1):
                        counter += lo[idx-1][jdx]
                    potencial_list[idx][jdx] = counter
        return potencial_list[idx_len-1][jdx_len-1]

myc = Solution()

possible_paths = myc.get_number_of_possible_paths([[0,0,-1,0],
                                                   [0,0,-1,0],
                                                   [0,0,0,0]])

print("There is {0} possible paths".format(possible_paths))