edu.umd.cfar.lamp.viper.util
Class Combinator

java.lang.Object
  edu.umd.cfar.lamp.viper.util.Combinator

public class Combinator

extends java.lang.Object

This class takes in an array of Objects and runs through all possible k-combinations. See Doug Moore's Bit Twiddling.

Author:

David Mihalcik

See Also:

Permuter

Constructor Summary

Combinator(java.lang.Object[] set, int lengthOfPermutation)
Constructs a new Combinator to iterate through all combinations of the specified length on the given set.

Method Summary

java.lang.Object[]	getCurrentCombination() Returns the most recently generated combination.
java.lang.Object[]	getNextCombination() Returns the lexicographically next combination.
protected java.math.BigInteger	leastItem(java.math.BigInteger comb) Returns the least item in a combination.
java.lang.String	toString() Prints out the last combination.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Combinator

public Combinator(java.lang.Object[] set,
                  int lengthOfPermutation)

Constructs a new Combinator to iterate through all combinations of the specified length on the given set.

Parameters:

set - The data to iterate over.

lengthOfPermutation - The length of the sets to generate.

Method Detail

leastItem

protected java.math.BigInteger leastItem(java.math.BigInteger comb)

Returns the least item in a combination. eg if bits 2, 4, and 5 are set, returns an int with just bit 2 set (4).

Parameters:

comb - The combination to find the least set bit in.

Returns:

A number with just one bit set, the least significant of those set in the parameter.

getNextCombination

public java.lang.Object[] getNextCombination()

Returns the lexicographically next combination.

Returns:

The next combination.

getCurrentCombination

public java.lang.Object[] getCurrentCombination()

Returns the most recently generated combination.

Returns:

The last combination.

toString

public java.lang.String toString()

Prints out the last combination.

Returns:

The last combination with french braces and comma seperated.