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全排列的一种递归算法

摘要: 全排列的一种递归算法

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全排列的一种递归算法:
来自:http://blog.sina.com.cn/u/3ee207aa010002y2

import java.util.*;

public class PermutationAndCombination{

 /**

 * author:54powerman@163.com

 * blog:http://blog.sina.com.cn/m/54powerman

 **/

 public static void main(String[] args){

  long date1=System.currentTimeMillis();

  List list=count("abcde");//89abcdefghijklmnopqrstuvwxyz

  for(int i=0;i< list.size();i++){

   System.out.println(list.get(i));

  }

  System.out.println("Process complete!Get "+list.size()+" strings and take ");

  System.out.print(System.currentTimeMillis()-date1+" ms");

 }

 public static List count(String strData){

  List list = new ArrayList();

  if(strData.length()<2){

   list.add(strData);

   return list;

  }else if(strData.length()==2){

   String str1=strData.substring(0,1);

   String str2=strData.substring(1);

   list.add(strData);

   list.add(str2+str1);

  }else{

   for(int i=0;i < strData.length();i++){

    String strTmp=strData.substring(i,i+1);

    List listTmp=count(strData.substring(0,i)+strData.substring(i+1,strData.length()));

    for(int j=0;j< listTmp.size();j++)

    {

     list.add(strTmp+listTmp.get(j).toString());

    }

   }

  }

  return list;

 }

};

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运行结果:

C:\java>java PermutationAndCombination
abcde
abced
abdce
abdec
abecd
abedc
acbde
acbed
acdbe
acdeb
acebd
acedb
adbce
adbec
adcbe
adceb
adebc
adecb
aebcd
aebdc
aecbd
aecdb
aedbc
aedcb
bacde
baced
badce
badec
baecd
baedc
bcade
bcaed
bcdae
bcdea
bcead
bceda
bdace
bdaec
bdcae
bdcea
bdeac
bdeca
beacd
beadc
becad
becda
bedac
bedca
cabde
cabed
cadbe
cadeb
caebd
caedb
cbade
cbaed
cbdae
cbdea
cbead
cbeda
cdabe
cdaeb
cdbae
cdbea
cdeab
cdeba
ceabd
ceadb
cebad
cebda
cedab
cedba
dabce
dabec
dacbe
daceb
daebc
daecb
dbace
dbaec
dbcae
dbcea
dbeac
dbeca
dcabe
dcaeb
dcbae
dcbea
dceab
dceba
deabc
deacb
debac
debca
decab
decba
eabcd
eabdc
eacbd
eacdb
eadbc
eadcb
ebacd
ebadc
ebcad
ebcda
ebdac
ebdca
ecabd
ecadb
ecbad
ecbda
ecdab
ecdba
edabc
edacb
edbac
edbca
edcab
edcba
Process complete!Get 120 strings and take
40 ms
C:\java>

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