打印菱形

方法一：

for i in range(-3,4):
    if i < 0:
        a = -i
    else:
        a = i
    print(' ' * a + '*' *(7 - a * 2))

 

n = 9
e = n // 2
for i in range(-e,e+1):
    print('{:^{}}'.format('*' * (n - 2 * abs(i)),n))