Python-сообщество

import itertools
def iterator(myList):
    res = [myList]
    while(True):
        myDict = dict((itertools.izip(range(len(res[-1])),res[-1])))
        for i in reversed(myDict.keys()[1:]):
            if myDict[i] > myDict[i-1]:

                    minChar = min([x for x in myDict.values()[i:] if x > myDict[i-1]])
                    minCharIndex = dict_index(minChar,myDict)
                    myDict[minCharIndex],myDict[i-1] = myDict[i-1],myDict[minCharIndex]
                    if ((len(myDict.values()) - i)> 1):
                        myDict.update(invert_dict(sub_dict(myDict,myDict.keys()[i:])))
                    break
        if myDict.values() in res:
            return res
        res.append(myDict.values())


def invert_dict(d):
    return dict(itertools.izip(d.iterkeys( ),reversed(d.values( ))))
                            
def sub_dict(somedict, somekeys, default=None):
    return dict([ (k, somedict.get(k, default)) for k in somekeys ])

def dict_index(value,d):
    for key,item in d.items():
            if value == item:
                    return key
    else: raise ValueError, 'key not found'

print iterator(list('123'))

def recFac(x):
	if x <= 1:
		return 1
	else:
		return recFac(x-1)*x

for x in xrange(0,10000):
    try:
        recFac(x)
    except RuntimeError:
        print x
        break

out: 997