打印杨辉三角—Python

b=[]
for i in range(0,9):
    c=[]
    for j in range(0,i):
        if j==0:
            c.append(b[i-1][j])
        if j<=i-2:#执行完第一个if，接着执行第二个if
            c.append(b[i-1][j]+b[i-1][j+1])
    c.append(1)#每次循环结束b列表尾部添加1
    b.append(c)
# print(b)
for i in b:
    for k in i:
        print(k,end=" ")
    print()