class Solution:
    def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
        m, n = len(obstacleGrid), len(obstacleGrid[0])

        if not m or not n:
            return 0

        dp = [[0 for _ in range(n)] for _ in range(m)]

        # init
        if obstacleGrid[0][0] == 1:
            return 0
        else:
            dp[0][0] = 1 

        for i in range(1, m):
            if obstacleGrid[i][0] == 1:
                dp[i][0] = 0
            else:
                dp[i][0] = dp[i-1][0] 

        for j in range(1, n):
            if obstacleGrid[0][j] == 1:
                dp[0][j] = 0
            else:
                dp[0][j] = dp[0][j-1]

        # function
        for i in range(1, m):
            for j in range(1, n):
                if obstacleGrid[i][j] == 1:
                    dp[i][j] = 0
                else:
                    dp[i][j] = dp[i-1][j] + dp[i][j-1]

        # print(dp)
        # ans
        return dp[-1][-1]