全排列，精简

package 全排列;

import java.util.ArrayList;

public class Main {
	private static ArrayList<String> a = new ArrayList<String>();
	
	public static void main(String[] arg){
		String[] ss = {"1","2","3","4","5","6","7","8","9"};
		long begin = System.currentTimeMillis();
		pailie(0,ss.length-1,ss);
		
		for(int i=0;i<a.size();i++){
			System.out.println(a.get(i)+" ");
		}
		
		long end = System.currentTimeMillis();
		System.out.println((end-begin)/1000f+"秒");
	}
	
	public static void pailie(int start,int end,String[] ss){
		if(start==end){
			String s="";
			for(int i=0;i<ss.length;i++){
				s+=ss[i];
			}
			a.add(s);
		}
		
		for(int i=start;i<=end;i++){
			
			String index=ss[start];
			ss[start]=ss[i];
			ss[i]=index;
			
			pailie(start+1,end,ss);
			
			index=ss[start];
			ss[start]=ss[i];
			ss[i]=index;
		}
	}

}