Python程序员的进化

1 def factorial(x):
2     if x == 0:
3         return 1
4     else:
5         return x * factorial(x - 1)
6  print factorial(6)

1 def factorial(x):
2     result = 1
3     i = 2
4     while i <= x:
5         result = result * i
6         i = i + 1
7     return result
8  print factorial(6)

1 def fact(x): #{
2      result = i = 1;
3     while (i <= x): #{
4          result *= i;
5         i += 1;
6     #}
7      return result;
8  #}
9  print(fact(6))

1 @tailcall
2  def fact(x, acc=1):
3     if (x > 1): return (fact((x - 1), (acc * x)))
4     else:       return acc
5 print(fact(6))

1 def Factorial(x):
2     res = 1
3     for i in xrange(2, x + 1):
4         res *= i
5     return res
6 print Factorial(6)

1 def fact(x):
2     return x > 1 and x * fact(x - 1) or 1
3 print fact(6)

1 f = lambda x: x and x * f(x - 1) or 1
2 print f(6)

1 import operator as op
2 import functional as f
3 fact = lambda x: f.foldl(op.mul, 1, xrange(2, x + 1))
4 print fact(6)

1 import sys
2 @tailcall
3 def fact(x, acc=1):
4     if x: return fact(x.__sub__(1), acc.__mul__(x))
5     return acc
6 sys.stdout.write(str(fact(6)) + '\n'

1 import c_math
2 fact = c_math.fact
3 print fact(6)

1 import c_maths
2 fact = c_maths.fact
3 print fact(6)

 1 def factorial(x):
 2     #-------------------------------------------------
 3     #--- Code snippet from The Math Vault          ---
 4     #--- Calculate factorial (C) Arthur Smith 1999 ---
 5     #-------------------------------------------------
 6     result = str(1)
 7     i = 1 #Thanks Adam
 8     while i <= x:
 9         #result = result * i  #It's faster to use *=
10         #result = str(result * result + i)
11            #result = int(result *= i) #??????
12         result str(int(result) * i)
13         #result = int(str(result) * i)
14         i = i + 1
15     return result
16 print factorial(6)

1 import os
2 def fact(x):
3     os.system('factorial ' + str(x))
4 fact(6)

 1 NULL = None
 2 def CalculateAndPrintFactorialEx(dwNumber,
 3                                  hOutputDevice,
 4                                  lpLparam,
 5                                  lpWparam,
 6                                  lpsscSecurity,
 7                                  *dwReserved):
 8     if lpsscSecurity != NULL:
 9         return NULL #Not implemented
10     dwResult = dwCounter = 1
11     while dwCounter <= dwNumber:
12         dwResult *= dwCounter
13         dwCounter += 1
14     hOutputDevice.write(str(dwResult))
15     hOutputDevice.write('\n')
16     return 1
17 import sys
18 CalculateAndPrintFactorialEx(6, sys.stdout, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL)

 1 def new(cls, *args, **kwargs):
 2     return cls(*args, **kwargs)
 3  
 4 class Number(object):
 5     pass
 6  
 7 class IntegralNumber(int, Number):
 8     def toInt(self):
 9         return new (int, self)
10  
11 class InternalBase(object):
12     def __init__(self, base):
13         self.base = base.toInt()
14  
15     def getBase(self):
16         return new (IntegralNumber, self.base)
17  
18 class MathematicsSystem(object):
19     def __init__(self, ibase):
20         Abstract
21  
22     @classmethod
23     def getInstance(cls, ibase):
24         try:
25             cls.__instance
26         except AttributeError:
27             cls.__instance = new (cls, ibase)
28         return cls.__instance
29  
30 class StandardMathematicsSystem(MathematicsSystem):
31     def __init__(self, ibase):
32         if ibase.getBase() != new (IntegralNumber, 2):
33             raise NotImplementedError
34         self.base = ibase.getBase()
35  
36     def calculateFactorial(self, target):
37         result = new (IntegralNumber, 1)
38         i = new (IntegralNumber, 2)
39         while i <= target:
40             result = result * i
41             i = i + new (IntegralNumber, 1)
42         return result
43  
44 print StandardMathematicsSystem.getInstance(new (InternalBase, new (IntegralNumber, 2))).calculateFactorial(new (IntegralNumber, 6))