From: ashu on 4 Sep 2009 00:28 Hi, I've a requirement as follows: If I give parameter as 3 to a script, it should give following combination of numbers: 1 2 3 12 13 23 123 If I give parameter as 4 to a script, it should give following combination of numbers: 1 2 3 4 12 13 14 23 24 34 123 124 134 234 1234  The number of combination would be (2^n)  1. Could some one please help finding the logic/script for this? Thank you, Ashok M +919663398009
From: Ben Finney on 4 Sep 2009 01:34 ashu <ashu.magadum(a)gmail.com> writes: > I've a requirement as follows: What's causing this requirement? It sounds like a homework assignment. What realworld problem is being addressed? > If I give parameter as 3 to a script, it should give following > combination of numbers: > > 1 > 2 > 3 […] > 123 > > If I give parameter as 4 to a script, it should give following > combination of numbers: > > 1 > 2 > 3 […] > 234 > 1234 >  > > The number of combination would be (2^n)  1. > > Could some one please help finding the logic/script for this? I would suggest using a language with combinations already implemented in a standard library. Python is a good choice: $ python2.6 […] >>> import itertools >>> def sequence_combinations(seq_len): ... seq_full = range(1, seq_len+1) ... generators = itertools.chain( ... *(itertools.combinations(seq_full, sub_len) ... for sub_len in range(1, seq_len+1))) ... result = list(generators) ... return result ... >>> sequence_combinations(3) [(1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)] >>> sequence_combinations(4) [(1,), (2,), (3,), (4,), (1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4), (1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4), (1, 2, 3, 4)] >>> # to make it a bit clearer: >>> import pprint >>> pprint.pprint(sequence_combinations(4)) [(1,), (2,), (3,), (4,), (1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4), (1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4), (1, 2, 3, 4)]  \ “What's another word for Thesaurus?” —Steven Wright  `\  _o__)  Ben Finney

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