Liu, Shi's solution of permutation of 7 number.

liushi_7_perm.java

package demo;

import java.util.ArrayList;
import java.util.List;

public class demo {

	static List<String> cout(List<String> one,String str){
		
		List<String> t = new ArrayList<String>();
		for(int i =0;i<one.size();i++){
			char[] s = one.get(i).toCharArray();
			t.add(str+one.get(i));
			for(int j=0;j<s.length;j++){
				String st = one.get(i).substring(0, j+1);
				String sst = one.get(i).substring(j+1);
				t.add(st+str+sst);
			}
		}
		return t;
	}
	public static void main(String[] args) {
		String temp[] = {"1","2","3","4","5","6","7"};
		List<String> s = new ArrayList<String>();
		s.add(temp[0]);
		for(int i = 1;i<temp.length;i++)
			s = cout(s,temp[i]);
		for(int i = 0;i<s.size();i++)
			System.out.println((i+1)+"--"+s.get(i));
	}
}