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;}}}