Java permutation and combination algorithm

1. Full Sorting Algorithm

Import java. util. ArrayList;/*** full Sorting Algorithm **/public class Arrange {private int total = 0; private ArrayList
 ArrangeList = new ArrayList
 (); Public Arrange () {} private void swap (String list [], int k, int I) {String c3 = list [k]; list [k] = list [I]; list [I] = c3;} public void perm (String list [], int k, int m) {if (k> m) {StringBuffer sb = new StringBuffer (); for (int I = 0; I <= m; I ++) {sb. append (list [I]). append (",");} if (sb. length ()> 0) {sb. setLength (sb. length ()-1);} arrangeList. add (sb. toString (); total ++;} else {for (int I = k; I <= m; I ++) {swap (list, k, I ); perm (list, k + 1, m); swap (list, k, I) ;}} public int getTotal () {return total;} public ArrayList
 GetArrangeList () {return arrangeList;} public static void main (String args []) {String list [] = {"1", "2", "3 ", "4", "5"}; Arrange ts = new Arrange (); ts. perm (list, 0, list. length-1); for (int I = 0; I <ts. getArrangeList (). size (); I ++) {System. out. println (ts. getArrangeList (). get (I);} System. out. println ("total:" + ts. total );}}

2. combination algorithms

Import java. util. ArrayList; import java. util. BitSet; public class Combination {private ArrayList
 CombList = new ArrayList
 (); Public void mn (String [] array, int n) {int m = array. length; if (m <n) throw new IllegalArgumentException ("Error m <n"); BitSet bs = new BitSet (m); for (int I = 0; I <n; I ++) {bs. set (I, true) ;}do {printAll (array, bs) ;}while (moveNext (bs, m ));} /*** 1. start the start position of the first true segment, end position * 2. Set the first true segment to false * 3. Set the value of the array from 0 subscript to true * 4 when the number of elements in the first true segment is reduced to the position of the next object. set the end position of the first true segment to true ** @ param bs indicates whether the flag is displayed * @ pa Ram m array length * @ return boolean whether there are other combinations */private boolean moveNext (BitSet bs, int m) {int start =-1; while (start <m) if (bs. get (++ start) break; if (start> = m) return false; int end = start; while (end <m) if (! Bs. get (++ end) break; if (end> = m) return false; for (int I = start; I <end; I ++) bs. set (I, false); for (int I = 0; I <end-start-1; I ++) bs. set (I); bs. set (end); return true ;} /*** output the generated combination result ** @ param array * @ param bs array element indicates whether the flag set is displayed */private void printAll (String [] array, bitSet bs) {StringBuffer sb = new StringBuffer (); for (int I = 0; I <array. length; I ++) if (bs. get (I) {sb. append (array [I]). append (',');} sb. setLength (sb. length ()-1); combList. add (sb. toString ();} public ArrayList
 GetCombList () {return combList;} public static void main (String [] args) throws Exception {Combination comb = new Combination (); comb. mn (new String [] {"1", "2", "3", "4", "5", "6"}, 3 ); for (int I = 0; I <comb. getCombList (). size (); I ++) {System. out. println (comb. getCombList (). get (I); String [] list = comb. getCombList (). get (I ). split (","); Arrange ts = new Arrange (); ts. perm (list, 0, list. length-1); for (int j = 0; j <ts. getArrangeList (). size (); j ++) {System. out. println ("/u0009" + ts. getArrangeList (). get (j ));}}}}

3. Call the permutation and combination algorithm tool class

import java.util.ArrayList;public class ArrangeCombine {public static ArrayList
   getArrangeOrCombine(String[] args,int n, boolean isArrange) throws Exception{if (args.length<=0) {throw new Exception("array.length<=0");}if (n>args.length) {throw new Exception(" n>array.length");}Combination comb = new Combination();comb.mn(args, n);if (!isArrange) {return comb.getCombList();}ArrayList
   arrangeList = new ArrayList
  ();for (int i = 0; i < comb.getCombList().size(); i++) {String[] list = comb.getCombList().get(i).split(",");Arrange ts = new Arrange();ts.perm(list, 0, list.length-1);for (int j = 0; j < ts.getArrangeList().size(); j++) {arrangeList.add(ts.getArrangeList().get(j));}}return arrangeList;}public static void main(String[] args) {try {ArrayList
   arrangeOrCombine = ArrangeCombine.getArrangeOrCombine(new String[]{"1","2","3","4","5","6"}, 3, false);ArrayList
   arrangeOrCombine2 = ArrangeCombine.getArrangeOrCombine(new String[]{"1","2","3","4","5","6"}, 3, true);for (int i = 0; i < arrangeOrCombine.size(); i++) {System.out.println(arrangeOrCombine.get(i));}System.out.println("Total:"+arrangeOrCombine.size());System.out.println("=============================");for (int i = 0; i < arrangeOrCombine2.size(); i++) {System.out.println(arrangeOrCombine2.get(i));}System.out.println("Total:"+arrangeOrCombine2.size());} catch (Exception e) {e.printStackTrace();}}}