2010-12-21 150 views
8

我怎么能在一个递归函数结合这两个函数产生这样的结果:递归阶乘函数

factorial(6) 
1! = 1 
2! = 2 
3! = 6 
4! = 24 
5! = 120 
6! = 720 

这些代码

def factorial(n): 
    if n <1: # base case 
     return 1 
    else: 
     return n * factorial(n - 1) # recursive call 
def fact(n): 
     for i in range(1, n+1): 
       print "%2d! = %d" % (i, factorial(i)) 

fact(6) 
1! = 1 
2! = 2 
3! = 6 
4! = 24 
5! = 120 
6! = 720 

当你看到这两个的执行给出了一个正确的答案,我只想把它做成一个递归函数。

+4

我没有得到任何理由都合并成一个功能。 – mqpasta 2010-12-21 18:08:29

+1

嗯。这是功课吗?你试过什么了? – 2010-12-21 18:08:44

+0

不要。它看起来很好。把它们结合起来会让事情变得更加困难。 – FrustratedWithFormsDesigner 2010-12-21 18:08:48

回答

19
def factorial(n): 
    if n <1: # base case 
     return 1 
    else: 
     returnNumber = n * factorial(n - 1) # recursive call 
     print(str(n) + '! = ' + str(returnNumber)) 
     return returnNumber 
2

我对Python没有经验,但是像这样?

def factorial(n): 
    if n <1: # base case 
     return 1 
    else: 
     f = n * factorial(n - 1) # recursive call 
     print "%2d! = %d" % (n, f) 
     return f 
2

试试这个:

def factorial(n): 
    if n <1: # base case 
     print "%2d! = %d" % (n, n) 
     return 1 
    else: 
     temp = factorial(n - 1) 
     print "%2d! = %d" % (n, n*temp) 
     return n * temp # recursive call 

一件事我注意到的是,你正在返回“1”当n < 1,这意味着你的函数将返回1甚至为负数。你可能想解决这个问题。

4
def factorial(n): 
    result = 1 if n <= 1 else n * factorial(n - 1) 
    print '%d! = %d' % (n, result) 
    return result 
1

这是功课任何机会?

def traced_factorial(n): 
    def factorial(n): 
    if n <= 1: 
     return 1 
    return n * factorial(n - 1) 
    for i in range(1, n + 1): 
    print '%2d! = %d' %(i, factorial(i)) 

PEP227了解更多详情。简而言之,Python允许您在函数内定义函数。

1

一个更

def fact(x): 
    if x == 0: 
     return 0 
    elif x == 1: 
     return 1 
    else: 
     return x * fact(x-1) 

for x in range(0,10): 
    print '%d! = %d' %(x, fact(x)) 
5

短之一:

def fac(n): 
    if n == 0: 
     return 1 
    else: 
     return n * fac(n-1) 
print fac(0) 
18

2行代码:

def fac(n): 
    return 1 if (n < 1) else n * fac(n-1) 

测试它:

print fac(4) 

结果:

24 
1
fac = lambda x: 1 if x == 0 else x * fac(x - 1) 
0

如果你想从用户获取输入!

def factorial(number): 
    return 1 if (number<1) else number * factorial(number-1) 

n = int(input().strip()) 

print("n! = 1", end="") 

for num in range(2, n+1): 
    print(" x {}". format(num), end="") 


print(" = {}".format(factorial(n))) 
0

我真的不知道负数的阶乘,但是这将与所有N> = 0工作:

def factorial(n): 
if n >= 0: 
    if n == 1 or n==0: 
     return 1 
    else: 
     n = n * factorial(n-1) 
     return n 
else: 
    return 'error'