Permutations

[Lin Shen]

Hello. I need to write a program which can do permutations. E.g
cat
cta
act
atc
tca
tac
will be printed out if the imput cat is given on the command line. Similarly, 24 different combinations should be printed out if a String with 4 characters are given.
The code I written is shown below:

 
public class Permutations{
   public static void permutations(String input){
      int length = input.length();
      if(length == 1){
          System.out.println(input);
      }
       
      else{
           char[] c = new char[length];
           c = input.toCharrArray();
           int i = 0;
           String input2 = "":
           for(; i < length; i++){
               input2 = input.substring(0, i) + 
                   input.substring(i + 1, length);
               System.out.println(c[i]);
               permutations(input2);
           }
       }
   }

   public static void main(String[] args)
       permutations(args[0]);
   }
}
 

The result I got missed first few characters for each combination. Could anyone help me to fix it? If you think my idea is totally wrong, please give me some hints, please.

[Herb Schildt]

I tried compiling the code that you posted but got a number of compiler errors. Could repost a clean copy of your program?

[fred rosenberger]

I couldn't get this code to compile without a few changes. even then, it wouldn't run - getting a "java.lang.NoClassDefFoundError: Permutations" error.
are you sure the code you posted was correct?
sorry for the duplicate post, i was typing mine when Herb posted his.
[ October 08, 2003: Message edited by: fred rosenberger ]

[Lin Shen]

[Lin Shen]

Sorry. The copy/paste does not work. I therefore typed my code by hand. Here is the code again.

 
public class Permutations{
   public static void permutations(String input){
      int length = input.length();
      if(length == 1){
          System.out.println(input);
      }
       
      else{
           char[] c = new char[length];
           c = input.toCharrArray();
           int i = 0;
           String input2 = "";
           for(; i < length; i++){
               char ch = c[i];
               input2 = input.substring(0, i) + 
                   input.substring(i + 1, length);
               System.out.print(ch);
               permutations(input2);
           }
       }
   }

public static void main(String[] args)
permutations(args[0]);
}
}

 

[Lin Shen]

I have solved this problem!!! I am so happy now.

[Herb Schildt]

I am happy that your problem is fixed!