[puzzle]
Anton Vredegoor
anton at vredegoor.doge.nl
Mon Dec 29 02:35:30 CET 2003
While trying to solve Glen Wheelers problem I discovered an
interesting puzzle. I'm going away for a day or so and it would be
nice to have it solved when I'm back.
It's about a different way to generate the so-called antonian numbers
(still trying to find a better name) but now in lexicographically
sorted order. I have found a generator for them but as yet I have no
way to directly compute "sorted reflected" integers from a normal
integer sequence. I hope my code is more clear than my question ...
One hint, ISTMT in order to get at a "sorted reflected" integer
sequence there has to be a fixed maximum number, while the antonian
digits function is infinite. Anyway, it's much too late and I had too
much coffee, so maybe it's trivial ...
Anton
class AntonianSorted:
def __init__(self, n, k):
self.limits = [k for i in range(n)]
self.state = []
self.iterator = self.__gen__()
def __iter__(self): return self
def next(self): return self.iterator.next()
def __gen__(self):
state, limits = self.state, self.limits
while 1:
if len(state) < len(limits):
state.append(0)
else:
i = len(state)-1
while i > 0 and state[i] == limits[i]-1:
state.pop()
i -= 1
if state[i] < limits[i]-1:
state[i] += 1
else:
raise StopIteration
yield state[:]
def antonianvalue(seq, base):
return reduce(lambda x,y: x*base+y+1,seq,0)-1
def antoniandigits(val, base):
res = []
while val > -1:
res.append(val % base)
val = val/base-1
res.reverse()
return res
def product(L): return reduce(lambda x,y: x*y,L,1)
def xproduct(n,k):
res = 0
for i in range(1,n+1):
res += product([k]*i)
return res
def test():
ndigits, base = 3,3
A = AntonianSorted(ndigits,base)
for i,x in enumerate(A):
a = antonianvalue(x, base)
d = antoniandigits(i, base)
print "%2i <==> %2i %9s <==> %9s" %(i,a,x,d)
print
for i in xrange(xproduct(ndigits,base)):
print "%2i <==> ??" %(i)
if __name__=='__main__':
test()
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