usr bin env python def primes if return elif return range mroot half 2

  • Anonymous
  • Python
  • 28 Jun 2009 
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#! /usr/bin/env python



def primes(n): 

	if n==2: return [2]

	elif n<2: return []

	s=range(3,n+1,2)

	mroot = n ** 0.5

	half=(n+1)/2-1

	i=0

	m=3

	while m <= mroot:

		if s[i]:

			j=(m*m-3)/2

			s[j]=0

			while j<half:

				s[j]=0

				j+=m

		i=i+1

		m=2*i+3

	return [2]+[x for x in s if x]



def dec2rim(n):

	rim=''

	d={1:'I',4:'IV',5:'V',9:'IX',10:'X',40:'XL',50:'L'}

	while n!=0:

		for i in [50,40,10,9,5,4,1]:

			if i<=n:

				n=n-i

				rim+=d[i]

				break

	return rim



# MMMCMXCIX = 3999



answer = ''.join([dec2rim(i) for i in primes(3999)]).count('X')

print answer



>>> ================================ RESTART ================================

>>> 

903
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