78 Subsets

Given a set of distinct integers, S, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

 

For example,
If S = [1,2,3], a solution is:

DSF:和combination 的方法一样，再加一个控制mem.size 的外层循坏！

package leetcode2;

import java.util.*;

public class subset {

   public static ArrayList<ArrayList<Integer>> subset(int[] n){

  ArrayList<ArrayList<Integer>> res=new ArrayList<ArrayList<Integer>>();

  ArrayList<Integer> mem=new ArrayList<Integer>();

  int deep=0;

  for(int i=0;i<=n.length;i++){

  dfs(res,mem,deep,n,i);

  }

  return res;

   }

public static void dfs(ArrayList<ArrayList<Integer>> res,

ArrayList<Integer> mem, int deep,int[] n,int i) {

// TODO Auto-generated method stub

if(mem.size()==i){

ArrayList<Integer> re= new ArrayList<Integer>(mem) ;

Collections.sort(re);

if(!res.contains(re)){

res.add(re);

}

return;

}

for(int i1=deep;i1<n.length;i1++){

mem.add(n[i1]);

dfs(res,mem,i1+1,n,i);

if(mem.size()>0){

mem.remove(mem.size()-1) ;

}

 

}

 

}

public static void main(String[] args) {

// TODO Auto-generated method stub

      int[] a={1,2,3,8};

      System.out.println(subset(a));

}

 

}