COMBINATION_LOCK
The Combination Lock Problem

COMBINATION_LOCK is a MATLAB program which simulates the process of determining the combination of a lock.

This program demonstrates the method of exhaustive search, that is, it searches for an answer by trying every possibility. This requires a way of logically ordering the possibilities.

Usage:

combination_lock ( m, n, c )

• m, the number of dials (perhaps 3).
• n, the number of symbols on each dial (perhaps 10);
• c, a vector of length m, containing the combination, which should be integers in the range 0 to n-1. (perhaps [7,4,9]).

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

COMBINATION_LOCK is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

COMBO, a MATLAB library which includes many combinatorial routines.

PARTITION_PROBLEM, a MATLAB library which seeks solutions of the partition problem, splitting a set of integers into two subsets with equal sum.

SATISFY, a MATLAB program which demonstrates, for a particular circuit, an exhaustive search for solutions of the circuit satisfiability problem.

SUBSET, a MATLAB library which enumerates combinations, partitions, subsets, index sets, and other combinatorial objects.

SUBSET_SUM, a MATLAB library which seeks solutions of the subset sum problem.

Reference:

1. Donald Kreher, Douglas Simpson,
   Combinatorial Algorithms,
   CRC Press, 1998,
   ISBN: 0-8493-3988-X,
   LC: QA164.K73.
2. Silvano Martello, Paolo Toth,
   Knapsack Problems: Algorithms and Computer Implementations,
   Wiley, 1990,
   ISBN: 0-471-92420-2,
   LC: QA267.7.M37.

Source Code:

• bicycle_lock.m, the program for a (3,10) bicycle combination lock.
• combination_lock.m, the program for a general (m,n) combination lock.

Examples and Tests:

• bicycle_lock_output.txt, the output from the commmand bicycle_lock ( ).
• combination_lock_output.txt, the output from the commmand combination_lock ( 4, 5, [1,2,3,4] ).

You can go up one level to the MATLAB source codes.