# Program to find minimum number of cells it will take to reach bottom right corner in Python

PythonServer Side ProgrammingProgramming

Suppose we have a 2D grid representing a maze where 0 is for empty space, and 1 is the wall. We will start at grid[0, 0], we have to find the minimum number of squares it would take to get to bottom right corner of the grid. If we cannot reach, return −1.

So, if the input is like

 0 0 0 1 0 0 1 0 0

then the output will be 5

To solve this, we will follow these steps −

• R := row count of grid, C := column count of grid

• q := [0, 0, 1] when A[0, 0] is 1 otherwise a new list

• A[0, 0] := 1

• for each (r, c, d) in q, do

• if (r, c) is same as (R − 1, C − 1), then

• return d

• for each (x, y) in [(r + 1, c) ,(r − 1, c) ,(r, c + 1) ,(r, c − 1) ], do

• if x in range 0 to R and y in range 0 to C and A[x, y] is same as 0, then

• A[x, y] := 1

• insert (x, y, d + 1) at the end of q

• return −1

Let us see the following implementation to get better understanding −

## Example

Live Demo

class Solution:
def solve(self, A):
R, C = len(A), len(A[0])
q = [(0, 0, 1)] if not A[0][0] else []
A[0][0] = 1
for r, c, d in q:
if (r, c) == (R − 1, C − 1):
return d
for x, y in [(r + 1, c), (r − 1, c), (r, c + 1), (r, c −1)]:
if 0 <= x < R and 0 <= y < C and A[x][y] == 0:
A[x][y] = 1
q.append((x, y, d + 1))
return −1
ob = Solution()
grid = [
[0, 0, 0],
[1, 0, 0],
[1, 0, 0]
]
print(ob.solve(grid))

## Input

grid = [ [0, 0, 0], [1, 0, 0], [1, 0, 0] ]

## Output

5
Published on 21-Oct-2020 12:03:47