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文章作者：Tyan

1. 问题描述

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

Note: The solution set must not contain duplicate subsets.

For example,

[  [3],  [1],  [2],  [1,2,3],  [1,3],  [2,3],  [1,2],  []]

2. 求解

递归法

这道题类似于数组的组合问题，可以用递归法求解。N个数中每个数都分为要与不要两种情况，求解的过程如下图。递归的边界条件为N个数都遍历完了。

public class Solution {    public static List
   
    
     > result = new ArrayList
     
      
       >();    public List
       
        
         > subsets(int[] nums) { result.clear(); result.add(new ArrayList
         
          ()); combination(nums, 0, new ArrayList
          
           ()); return result; } public void combination(int[] nums, int index, List
           
             list) { if(index == nums.length) { return; } combination(nums, index + 1, new ArrayList
            
             (list)); list.add(nums[index]); result.add(list); combination(nums, index + 1, new ArrayList
             
              (list)); }}
             
            
           
          
         
        
       
      
     
    
   

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