[LeetCode]Subsets

Given a set of distinct integers, nums, 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 nums = [1,2,3], a solution is:

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

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题解:使用递归

code：

public class Solution {
    public List<List<Integer>> subsets(int[] nums) {
        
        Arrays.sort(nums);
        List<List<Integer>> ans = new ArrayList<List<Integer>>();
        List<Integer> res = new ArrayList<Integer>();
       sovle(0, nums.length, nums, res, ans);
        return ans;
    }
    private void sovle(int cur ,int length, int[] nums, List<Integer> res,  List<List<Integer>> ans)
    {
       ans.add(new ArrayList<Integer>(res));
       for(int i = cur; i<length; i++)
       {
           res.add(nums[i]);
           sovle(i+1 ,length, nums, res, ans);
           res.remove(res.size() - 1);
       }
    }
}