Python 实现巴斯卡三角形

def barska(n):
    res = [1]
    for i in range(n):
        print ('  '*(n-i)),
        res.insert(0, 0)
        for j in range(len(res)-2):
            res[j] += res[j+1]
            print ('%3d' %res[j]),
        res[len(res)-2] = 1
        print ('%3d' %res[len(res)-2]),
        print ''