题目：

题解：

class Solution {List<Integer> t = new ArrayList<Integer>();List<List<Integer>> ans = new ArrayList<List<Integer>>();public List<List<Integer>> subsets(int[] nums) {dfs(0, nums);return ans;}public void dfs(int cur, int[] nums) {if (cur == nums.length) {ans.add(new ArrayList<Integer>(t));return;}t.add(nums[cur]);dfs(cur + 1, nums);t.remove(t.size() - 1);dfs(cur + 1, nums);}
}