Write a method to return all subsets of a set.

CC150-9.4.java

package POJ;

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

public class Main{
 
	/**
	 * 
	 * 9.4 Write a method to return all subsets of a set.
	 * 
	 * 
	 */
	public static void main(String[] args) {
		Main so = new Main();
		int[] s={0,1,2};
		List<List<Integer>> RESULT=so.subsets(s);
		for(List<Integer> temp:RESULT){
			for(int i=0;i<temp.size();i++)
				System.out.print(temp.get(i)+" ");
			System.out.println();
		}
		
	}
	public List<List<Integer>> subsets(int[] S) {
        List<List<Integer>> result=new ArrayList<List<Integer>>();
        List<Integer> tmp=new ArrayList<Integer>();
        result.add(tmp);
        Arrays.sort(S);
        dfs(result,tmp,S,0);
        return result;
    }

	private void dfs(List<List<Integer>> result, List<Integer> tmp, int[] s,int depth) {
		// TODO Auto-generated method stub
		for(int i=depth;i<s.length;i++){
			tmp.add(s[i]);
			result.add(new ArrayList<Integer>(tmp));
			dfs(result,tmp,s,i+1);
			tmp.remove(tmp.size()-1);
		}
	}
}