001 /* Copyright 2004-2006 Stefan Ram.
002 This program is free software; you can redistribute it and/or modify
003 it under the terms of the GNU General Public License as published by
004 the Free Software Foundation; either version 2 of the License, or
005 (at your option) any later version.
006 This program is distributed in the hope that it will be useful,
007 but WITHOUT ANY WARRANTY; without even the implied warranty of
008 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
009 GNU General Public License for more details.
010 You should have received a copy of the GNU General Public License
011 along with this program; if not, write to the Free Software
012 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
013 package de.dclj.ram.system.iteration;
014
015 /** Enumerate all combinations of an array.
016 <pre><code>
017 import java.lang.String;
018 import java.lang.Object;
019 import de.dclj.ram.system.iteration.Combinations;
020 import static java.lang.System.out;
021 import java.util.Arrays;
022 // 2-combinations of "array" without repetition
023 // a combination of n things, taken t at a time
024 // i.e., select a subset of size t, t=subset size
025 // Kombinationen von "array" ohne Wiederholung zur Klasse 2.
026 public class Main
027 { public static void main( final String[] args )
028 { final Object[] array = new Object[]{ "T", "H", "E" };
029 for( final java.lang.Object[] o : new Combinations( 2, array ))
030 out.print( Arrays.toString( o )); }}
031 </code></pre>
032 <pre><code>
033 [T, H][T, E][H, E]
034 </code></pre>
035 @version slr@2008-04-25T05:47:49+02:00
036 @since slr@2007-06-05T08:12:16+02:00
037 @see <a HREF="http://www.purl.org/stefan_ram/java/de/dclj/ram/system/iteration/Combinations.java">source code</a>
038 @see <a HREF="http://www.purl.org/stefan_ram/html/ram.jar/de/dclj/ram/system/iteration/Combinations.html">documentation</a>
039 @see "<a href='http://www.purl.org/stefan_ram/pub/ram-jar'>Library homepage</a> (Must be opened in a <i>new window</i>, outside of frames, to avoid a 403 status code.)" */
040 @de.dclj.ram.meta.quality.Cleaned(2)
041 @de.dclj.ram.meta.description.Copyright("Copright 2006 Stefan Ram")
042 @de.dclj.ram.meta.description.TypePath("de.dclj.ram.ram.system.iteration.Combinations")
043 @de.dclj.ram.meta.description.Cleared("slr@2008-04-25T05:47:49+02:00")
044 public class Combinations /* de.dclj.ram.system.iteration.Combinations */
045 implements de.dclj.ram.system.iteration.Iteration<java.lang.Object[]> {
046
047 public final int zzSize;
048 public final java.lang.Object[] zzBase;
049 public final int zzLength;
050 public final int[] zzC;
051 public final java.lang.Object[] zzResult;
052 public boolean zzHasNext = true;
053
054 public Combinations(final int size, final java.lang.Object[] base) {
055 this.zzSize = size;
056 assert this.zzSize >= 0;
057 this.zzBase = base;
058 this.zzLength = this.zzBase.length;
059 assert this.zzLength >= this.zzSize;
060 this.zzResult = new java.lang.Object[this.zzSize];
061 zzC = new int[this.zzSize + 3];
062 {
063 int j;
064
065 for (j = 1; j <= this.zzSize; ++j) {
066 zzC[j] = j - 1;
067 }
068 zzC[this.zzSize + 1] = this.zzLength;
069 zzC[this.zzSize + 2] = 0;
070 }
071 advance();
072 }
073
074 public final boolean hasNext() {
075 return this.zzHasNext;
076 }
077
078 public void advance() {
079 for (int i = 1; i <= this.zzSize; ++i) {
080 this.zzResult[i - 1] = this.zzBase[this.zzC[i]];
081 }
082 }
083
084 public final java.lang.Object[] next() {
085 advance();
086 if (this.zzHasNext) {
087 int j;
088 {
089 for (j = 1; this.zzC[j] + 1 == this.zzC[j + 1]; ++j) {
090 this.zzC[j] = j - 1;
091 }
092 }
093 if (j > this.zzSize) {
094 this.zzHasNext = false;
095 } else {
096 this.zzC[j] = this.zzC[j] + 1;
097 }
098 } else {
099 throw new java.util.NoSuchElementException();
100 }
101 return this.zzResult;
102 }
103
104 public void remove() {
105 throw new java.lang.UnsupportedOperationException();
106 }
107
108 public java.util.Iterator<java.lang.Object[]> iterator() {
109 return this;
110 }
111 }