63-不同路径

class Solution:
    def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
        if obstacleGrid[0][0] == 1:
            return 0
        m = len(obstacleGrid[0])
        n = len(obstacleGrid)
        res = [[0 for _ in range(m)] for _ in range(n)]
        for i in range(m):
            if obstacleGrid[0][i] == 0:
                res[0][i] = 1
            else:
                break
        for i in range(n):
            if obstacleGrid[i][0] == 0:
                res[i][0] = 1
            else:
                break
        for i in range(1, n):
            for j in range(1, m):
                if obstacleGrid[i][j] == 0:
                    res[i][j] = res[i-1][j] + res[i][j-1]
        return res[n-1][m-1]