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COMBINATION_LOCK\ The Combination Lock Problem {#combination_lock-the-combination-lock-problem align=”center”} ============================

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COMBINATION_LOCK is a C++ 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.

Licensing: {#licensing align=”center”}

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

Languages: {#languages align=”center”}

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: {#related-data-and-programs align=”center”}

CHANGE_MAKING, a C++ library which considers the change making problem, in which a given sum is to be formed using coins of various denominations.

COMBO, a C++ library which includes many combinatorial routines.

KNAPSACK_01, a C++ library which uses brute force to solve small versions of the 0/1 knapsack problem;

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

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

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

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

TSP_BRUTE, a C++ program which reads a file of city-to-city distances and solves the traveling salesperson problem, using brute force.

Reference: {#reference align=”center”}

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: {#source-code align=”center”}

• combination_lock.cpp, the source code.
• combination_lock.hpp, the include file.

Examples and Tests: {#examples-and-tests align=”center”}

• combination_lock_prb.cpp, a sample calling program.
• combination_lock_prb_output.txt, the output file.

List of Routines: {#list-of-routines align=”center”}

• BICYCLE_LOCK finds the combination on a typical bicycle lock.
• COMBINATION_LOCK determines the combination of a lock.
• COMBINATION_NEXT generates lock combinations in lex order.
• GET_SEED returns a random seed for the random number generator.
• I4_MAX returns the maximum of two I4’s.
• I4_MIN returns the smaller of two I4’s.
• I4_UNIFORM returns a scaled pseudorandom I4.
• I4VEC_EQ is true if two I4VEC’s are equal.
• I4VEC_PRINT prints an I4VEC.
• R4_ABS returns the absolute value of an R4.
• R4_NINT returns the nearest integer to an R4.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C++ source codes.

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Last modified on 13 May 2012.