递归的全排列产生算法

package algorithm;

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

/**
 * 递归的全排列产生算法
 * @author ls
 *
 */
public class NumberPerm {
	
	public void swap(int a, int b, List<Integer> list) {
		int temp = list.get(b);
		list.set(b, list.get(a));
		list.set(a, temp);
	}
	
	public void perm(List<Integer> list,int start, int n) {
		if(start==n) {
			System.out.print("( ");
			for(int i=0;i<n;i++) {
				System.out.print(list.get(i)+"");
			} 
			System.out.print(" )\n");
		} else {
			for(int j=start;j<n;j++) {
				swap(start,j,list);
				perm(list,start+1,n);
				swap(start,j,list);
			}
		}
	}
	
	public static void main(String []args) {
		NumberPerm permMe = new NumberPerm();
		List<Integer> myList = new ArrayList<Integer> ();
		for(int i=0;i<4;i++) {
			myList.add(i);
		}
		permMe.perm(myList, 0, myList.size());
	}
	
	

}