一:题目

二:上码

class Solution {/**- 先排序- 树层去重:那么直接在从横向循环中去重即可*/List<List<Integer>> ans = new ArrayList<>();List<Integer> path = new ArrayList<>();public void getAns(int[] nums,int st) {ans.add(new ArrayList<>(path));for (int i = st; i < nums.length; i++) {if (i-1 >= st && nums[i] == nums[i-1]) continue;path.add(nums[i]);getAns(nums,i+1);path.remove(path.size()-1);}}  public List<List<Integer>> subsetsWithDup(int[] nums) {Arrays.sort(nums);getAns(nums,0);return ans;}   
}