org.apache.commons.numbers.combinatorics

Class Combinations.LexicographicComparator

java.lang.Object

org.apache.commons.numbers.combinatorics.Combinations.LexicographicComparator

All Implemented Interfaces:

Serializable, Comparator<int[]>

Enclosing class:

Combinations

public static class Combinations.LexicographicComparator
extends Object
implements Comparator<int[]>, Serializable

Defines a lexicographic ordering of the combinations. The comparison is based on the value (in base 10) represented by the digit (interpreted in base n) in the input array, in reverse order. For example if c is {3, 2, 1}, and n is 3, the method will return 18.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LexicographicComparator(int n, int k)

Method Summary

Modifier and Type	Method and Description
int	compare(int[] c1, int[] c2)
int	getK() Gets the number of elements in each combination.
int	getN() Gets the size of the set from which combinations are drawn.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

LexicographicComparator

public LexicographicComparator(int n,
                               int k)

Parameters:

n - Size of the set from which subsets are selected.

k - Size of the subsets to be enumerated.

Method Detail

getN

public int getN()

Gets the size of the set from which combinations are drawn.

Returns:

the size of the universe.

getK

public int getK()

Gets the number of elements in each combination.

Returns:

the size of the subsets.

compare

public int compare(int[] c1,
                   int[] c2)

Specified by:

compare in interface Comparator<int[]>

Throws:

IllegalArgumentException - if the array lengths are not equal to k.

IllegalArgumentException - if an element of the array is not within the interval [0, n).