Question

I have a phone number range, for example:

3331234-3332345

I need to write a function that converts it to list of prefixes:

3331234
...
3331239
333124
...
333129
33313
...
33319
33320
...
33322
333231
333232
333233
3332341
...
3332345

Question is not so easy. I don’t need to get a list of numbers between range start and end.

Answer 1

My working code. It not very quick, but working. Optimizations welcome.

def fill(root, prefix, value, parent, pkey):
    if len(prefix) > 1:
        if prefix[0] in root:
            fill(root[prefix[0]], prefix[1:], value, root, prefix[0])
            if pkey:
                if len(parent[pkey]) == 10:
                    parent[pkey] = value
        elif type(root) == type({}):
            root[prefix[0]] = {}
            fill(root[prefix[0]], prefix[1:], value, root, prefix[0])
            if pkey:
                if len(parent[pkey]) == 10:
                    parent[pkey] = value
    elif type(root) == type({}):
        root[prefix[0]] = value
        if pkey:
            if len(parent[pkey]) == 10:
                parent[pkey] = value
    return root

def compact(prefixes, current):
    if not type(prefixes) == type({}):
        return [current]
    else:
        rlist = []
        for k, v in prefixes.iteritems():
            rlist.extend(compact(v, current + k))
            continue
        return rlist

if __name__ == '__main__':
    plist = {}
    for x in range(4440000, 4490000):
        fill(plist, str(x), 'value', plist, None)
    #print plist
    print compact(plist, '')