63. Unique Paths II 动态规划

跟Unique Paths一样，也是使用动态规划的问题。
解决此题的方法也和之前一样，先建立一个与目标矩阵相同尺寸的矩阵，然后

class Solution:
    def uniquePathsWithObstacles(self, obstacleGrid):
        """
        :type obstacleGrid: List[List[int]]
        :rtype: int
        """
        m = len(obstacleGrid); n = len(obstacleGrid[0])
        res = [[0 for i in range(n)] for j in range(m)]
        for i in range(m):
            if obstacleGrid[i][0] == 0:
                res[i][0] = 1
            else:
                res[i][0] = 0
                break

        for i in range(n):
            if obstacleGrid[0][i] == 0:
                res[0][i] = 1
            else:
                res[0][i] = 0
                break
        for i in range(1, m):
            for j in range(1, n):
                if obstacleGrid[i][j] == 1: res[i][j] = 0
                else:
                    res[i][j] = res[i-1][j] + res[i][j-1]
        return res[m-1][n-1]