please i need explanation

Thomas Rachel nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915 at spamschutz.glglgl.de
Fri Jan 11 13:58:35 CET 2013


Am 11.01.2013 17:33 schrieb kwakukwatiah at gmail.com:

>> def factorial(n):
>>      if n<2:
>>               return 1
>>      f = 1
>>      while n>= 2:
>>          f *= n
>>          f -= 1
>>      return f
>>
>>
>>
> please it works.

I doubt this.

If you give n = 4, you run into an endless loop.


> but don’t get why the return 1 and the code below.

The "if n < 2: return 1" serves to shorten the calculation process 
below. It is redundant, as you have a "f = 1" and a "return f" for n < 2.

The code below first sets f, which holds the result, to 1 and then 
multiplies it by n in each step. As the loop should contain a 'n -= 1', 
n decreases by 1 every step, turning it into f = n * (n-1) * (n-2) * ... 
* 2 and then, as n is not >= 2 any longer, stops the loop, returning f.

HTH,

Thomas



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