题目

代码

class Solution {
    List< List<Integer> > result = new ArrayList<>();
    LinkedList<Integer> path = new LinkedList<>();
    boolean [] used ;
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        used = new boolean[nums.length];
        Arrays.sort(nums);
        backtracking(nums,0);
        return result;
    }
    public void backtracking(int[] nums, int startIndex) {
        result.add(new ArrayList<>(path));
        for(int i = startIndex; i < nums.length; i++ ) {
            if(i > 0 && nums[i] == nums[i - 1] && !used[i -1 ]) {
                continue;
            }
            path.add(nums[i]);
            used[i] = true;
            backtracking(nums,i + 1);
            used[i] = false;
            path.removeLast();
        }
    }
}