Check Travelsibility | Python Fiddle

import json

def find_next_coords(matrix, coords, travelled):
    [x, y] = coords
    left, right, down, up = [x, y - 1], [x, y + 1], [x + 1, y], [x - 1, y]

next_coords = list()

for coords in [left, right, down, up]:
        [coords_x, coords_y] = coords

if coords_x > 3 or coords_x < 0 or coords_y > 3 or coords_y < 0:
            continue
        already_travelled = False
        for travelled_coords in travelled:
            if travelled_coords[0] == coords_x and travelled_coords[1] == coords_y:
                already_travelled = True
                break
        if matrix[coords_x] and matrix[coords_x][coords_y] and not already_travelled:
            next_coords.append(coords)

return next_coords

def can_travel(matrix, start, end, travelled):
    [start_x, start_y] = start
    [end_x, end_y] = end

travelled.append(start)

if start_x == end_x and start_y == end_y:
        return True

next_coords_to_go = find_next_coords(matrix, start, travelled)

for coords in next_coords_to_go:
        if can_travel(matrix, coords, end, travelled):
            return True

return False

def check_traversilibility(matrix, start, end):

output = "no"

if matrix[start[0]][start[1]] == 0:
        print(output)
        exit()

if can_travel(matrix, start, end, list()):
        output = "yes"

print(output)

matrix = json.loads("[ [0, 1, 1, 1], [1, 1, 0, 1], [1, 0, 0, 1], [1, 1, 0, 0] ]")
start = json.loads("[ 0, 3 ]")
end = json.loads("[ 3, 1 ]")
    
check_traversilibility(matrix, start, end)

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