实用：python编写一个函数，能够接受一个参数n，n为正整数，上三角和下三角打印．要求数字必须对齐
案例一：
def fn(n):
lst = [ i for i in range(n,0,-1)]
print(lst)
c = len(str(n))-1
w1 = c+2
w2 = c+3
for i in range(n+1,1,-1):
space = [' ' for i in range(i-2)]
space.extend(lst[i-2:])
for i in range(-n,0):
if i > -(10**c):
print('{1:<{0}}'.format(w1,space[i]),end='')
else:
print('{1:<{0}}'.format(w2,space[i]),end='')
else:
print()
fn(11)
运行结果：
[11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
1
2 1
3 2 1
4 3 2 1
5 4 3 2 1
6 5 4 3 2 1
7 6 5 4 3 2 1
8 7 6 5 4 3 2 1
9 8 7 6 5 4 3 2 1
10 9 8 7 6 5 4 3 2 1
11 10 9 8 7 6 5 4 3 2 1
案例变形１：
def fn(n):
tail = " ".join((str(i) for i in range(n,0,-1)))
print(tail)
width = len(tail)
for i in range(1,n):
print("{:>{}}".format(" ".join([str(j) for j in range(i,0,-1)]),width))
print(tail)
fn(11)
运行结果：
11 10 9 8 7 6 5 4 3 2 1
1
2 1
3 2 1
4 3 2 1
5 4 3 2 1
6 5 4 3 2 1
7 6 5 4 3 2 1
8 7 6 5 4 3 2 1
9 8 7 6 5 4 3 2 1
10 9 8 7 6 5 4 3 2 1
11 10 9 8 7 6 5 4 3 2 1
案例二：
def fn(n):
lst = [ i for i in range(n,0,-1)]
print(lst)
c = len(str(n))-1
w1 = c+2
w2 = c+3
for i in range(n):
nums = lst[i:]
space = ['' for _ in range(i)]
line = space.extend(nums)
for i in range(-n,0):
if i > -(10**c):
print('{1:<{0}}'.format(w1,space[i]),end='')
else:
print('{1:<{0}}'.format(w2,space[i]),end='')
else:
print()
运行结果：
fn(11)
[11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
11 10 9 8 7 6 5 4 3 2 1
10 9 8 7 6 5 4 3 2 1
9 8 7 6 5 4 3 2 1
8 7 6 5 4 3 2 1
7 6 5 4 3 2 1
6 5 4 3 2 1
5 4 3 2 1
4 3 2 1
3 2 1
2 1
1
案例变形：
def fn(n):
tail = " ".join(str(i) for i in range(n,0,-1))
width = len(tail)
for i in range(n,0,-1):
print("{:>{}}".format(" ".join([str(j) for j in range(i,0,-1)]),width))
fn(11)
运行结果：
11 10 9 8 7 6 5 4 3 2 1
10 9 8 7 6 5 4 3 2 1
9 8 7 6 5 4 3 2 1
8 7 6 5 4 3 2 1
7 6 5 4 3 2 1
6 5 4 3 2 1
5 4 3 2 1
4 3 2 1
3 2 1
2 1
1