def diamond(n):
    for i in range(1,2*n+1,2):
        if i <= n+1:
            print(" "*((n-i)//2) + i*"*" + " "*((n-i)//2))
        else:print(" "*((i-n)//2) + (2*n-i)*"*" + " "*((i-n)//2))

n = 9
diamond(n)

第二种写法

#n = int(input())
m = (n - 1) // 2
for i in range(n):
    d = abs(i - m)
    stars = n - 2 * d
    print(' ' * d + '*' * stars)