[LeetCode][Python3] 980. Unique Paths III

Problem :

https://leetcode.com/problems/unique-paths-iii/

My Solution :

class Solution:

def uniquePathsIII(self, grid):

def dfs(r, c, remain):

if grid[r][c] == 2:

if remain == 0:

self.ans += 1

return

grid[r][c] = -1

for y, x in ((r+1, c), (r-1, c), (r, c+1), (r, c-1)):

if (0 <= y < len(grid) and

0 <= x < len(grid[0]) and

grid[y][x] in (0, 2)):

dfs(y, x, remain-1)

grid[r][c] = 0

self.ans = 0

remain = 0

for r in range(len(grid)):

for c in range(len(grid[0])):

if grid[r][c] in (0, 1):

remain += 1

if grid[r][c] == 1:

R, C = r, c

dfs(R, C, remain)

return self.ans