// @Title: 子集 II (Subsets II)
// @Author: qisiii
// @Date: 2024-09-20 00:28:17
// @Runtime: 1 ms
// @Memory: 42.7 MB
// @comment: 
// @flag: 
class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        Arrays.sort(nums);
    List<List<Integer>> result = new ArrayList<>();
        dfs(result, new ArrayList<>(), nums, 0);
        return result;
    }

    private void dfs(List<List<Integer>> result, List<Integer> list, int[] nums, int start) {
        result.add(new ArrayList<>(list));
        if (start == nums.length) {
            return;
        }
        HashSet<Integer> set=new HashSet<>();
        //排序需要color数组，因为存在顺序，所以不能单纯的往后剪枝
        //子集和组合都可以根据往后剪枝来处理
        //set永远是保证单轮次不重复处理
        for (int i = start; i < nums.length; i++) {
            if(set.contains(nums[i])){
                continue;
            }else{
                set.add(nums[i]);
            }
            list.add(nums[i]);
            dfs(result, list, nums, i + 1);
            list.remove(list.size() - 1);
        }
    }
}

// @Title: 子集 II (Subsets II)
// @Author: qisiii
// @Date: 2024-09-22 00:25:28
// @Runtime: 1 ms
// @Memory: 42.5 MB
// @comment: 
// @flag: 
class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        //排序是针对的向后剪枝方案的去重
        Arrays.sort(nums);
    List<List<Integer>> result = new ArrayList<>();
        dfs(result, new ArrayList<>(), nums, 0);
        return result;
    }

    private void dfs(List<List<Integer>> result, List<Integer> list, int[] nums, int start) {
        result.add(new ArrayList<>(list));
        if (start == nums.length) {
            return;
        }
        HashSet<Integer> set=new HashSet<>();
        //排序需要color数组，因为存在顺序，所以不能单纯的往后剪枝
        //子集和组合都可以根据往后剪枝来处理
        //set永远是保证单轮次不重复处理
        for (int i = start; i < nums.length; i++) {
            if(set.contains(nums[i])){
                continue;
            }else{
                set.add(nums[i]);
            }
            list.add(nums[i]);
            dfs(result, list, nums, i + 1);
            list.remove(list.size() - 1);
        }
    }
}

// @Title: 子集 II (Subsets II)
// @Author: qisiii
// @Date: 2024-09-20 00:29:12
// @Runtime: 1 ms
// @Memory: 42.5 MB
// @comment: 
// @flag: 
class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        //排序是针对的向后剪枝方案的去重
        Arrays.sort(nums);
    List<List<Integer>> result = new ArrayList<>();
        dfs(result, new ArrayList<>(), nums, 0);
        return result;
    }

    private void dfs(List<List<Integer>> result, List<Integer> list, int[] nums, int start) {
        result.add(new ArrayList<>(list));
        if (start == nums.length) {
            return;
        }
        HashSet<Integer> set=new HashSet<>();
        //排序需要color数组，因为存在顺序，所以不能单纯的往后剪枝
        //子集和组合都可以根据往后剪枝来处理
        //set永远是保证单轮次不重复处理
        for (int i = start; i < nums.length; i++) {
            if(set.contains(nums[i])){
                continue;
            }else{
                set.add(nums[i]);
            }
            list.add(nums[i]);
            dfs(result, list, nums, i + 1);
            list.remove(list.size() - 1);
        }
    }
}