unique path II

def uniquePathsWithObstacles(self, obstacleGrid):
        if len(obstacleGrid) == 0 or len(obstacleGrid[0]) == 0 or obstacleGrid[0][0] == 1 or obstacleGrid[len(obstacleGrid)-1][len(obstacleGrid[0])-1] == 1:
            return 0
        solution = [[abs(obstacleGrid[i][j]-1) for j in range(len(obstacleGrid[0]))] for i in range(len(obstacleGrid))]
        for row in range(len(obstacleGrid)):
            for col in range(len(obstacleGrid[0])):
                if row == 0 and col > 0 and solution[row][col] != 0: #iff no obstacle
                    solution[row][col] = solution[row][col-1]
                elif col == 0 and row > 0 and solution[row][col] != 0: #iff no obstacle
                    solution[row][col] = solution[row-1][col]
                elif row > 0 and col > 0 and solution[row][col] != 0: #iff no obstacle
                    solution[row][col] = solution[row-1][col] + solution[row][col-1]
        return solution[len(solution)-1][len(solution[0])-1]