求杨辉三角中的某个数,python实现

　　

m=int(input('line: ').strip().lstrip('0'))
while True:
    k=int(input('number: ').strip())
    if k == m or k == 1:
        print(1)
        exit(10)
    elif k > m:
        print('wrong')
        continue
    else:
        break


dim=list()
for b in range(m):
    dew=[1]
    dim.append(dew)
    if b == 0:
        continue
    for p in range(1,b):
        dew.append(dim[b-1][p-1]+dim[b-1][p])
    dew.append(1)

print(dim)
print(dim[m-1][k-1])

pre=[1]
for b in range(1,m):
    post=pre[:]
    post.append(0)
    pre=[]
    for p in range(len(post)):
        pre.append(post[p-1]+post[p])
print(pre)
print(pre[k-1])

pre=[1]
for b in range(1,m):
    post=pre[:]
    post.append(0)
    pre.append(1)
    for p in range(0,len(post)//2+1):
        pre[p]=post[p-1]+post[p]
        if p*2 != len(post)-1:
            # pre[-p-1]=pre[p]
            pre[len(post)-1-p]=pre[p]
print(pre[k-1])