Paths around walls

The map of a live-stream mini game is a grid. grid[i] is row i from the top, and grid[i][j] is cell j from the left in that row. If it is ".", you can pass through that cell, and if it is "#", the cell is a wall that you cannot pass through. Rows and columns are numbered from 0.

The character starts at the top-left cell and moves one cell at a time, only right or down, until it reaches the bottom-right cell. Complete the function solution, which returns the number of paths it can take. Two paths are different if at least one cell they pass through is different. If the starting cell or the goal cell is a wall, or there is no path at all, return 0. If the map has only one cell and it is not a wall, there is one path that does not move.

Function

solution(grid)

Constraints

• The length of grid (the number of rows) is from 1 to 30.
• All strings in grid have the same length (the number of cells in a row), from 1 to 30.
• The strings in grid are made of only "." and "#".
• The answer can be a very large number. Return it as a Python integer as it is, without taking a remainder.

Examples

Starter code

def solution(grid):
    answer = 0
    return answer