字符串全排列算法

 

public class Main {
      public static void main(String[] args) {
          Main main = new Main();
          Set<String> result = main.action("abc");
          for(String str : result){
              System.out.println(str);
          }
      }
      
     public Set<String> action(String p){
         if(p.length() == 1){
             Set<String> set = new HashSet<String>();
             set.add(p);
             return set;
         }
         Set<String> result = new HashSet<String>();
         for(int i=0;i<p.length();i++){
             String s = p.substring(i,i+1);
             String os = p.substring(0,i)+p.substring(i+1);
             
             Set<String> set = action(os);
             for(String str : set){
                 result.add(s+str);
             }
         }
         return result;
     }
 }