public List<List<Integer>> subsetsWithDup(int[] nums) {

List<List<Integer>> result = new ArrayList<>();

List<Integer> elem = new ArrayList<>();

result.add(elem);

Arrays.sort(nums);

for (int i = 0; i < nums.length; i++) {

int dupCount = 0;

while (((i + 1) < nums.length) && nums[i + 1] == nums[i]) {

dupCount++;

i++;

}

int size = result.size();

for (int j = 0; j < size; j++) {

elem = new ArrayList<>(result.get(j));

for (int k = 0; k <= dupCount; k++) {

elem.add(nums[i]);

result.add(new ArrayList<>(elem)); // 注意这里是要放在 for 循环里面的

}

}

}

return result;

}

}