数组子集

给定一个可能包含重复元素的整数数组 nums，返回该数组所有可能的子集（幂集）。

说明：解集不能包含重复的子集。

LeetCode:https://leetcode-cn.com/problems/subsets-ii

public class Main {

    public static void main(String[] args) {
        System.out.println(subsetsWithDup(new int[]{1,2,2}));
    }

    public static List<List<Integer>> subsetsWithDup(int[] nums) {
        Arrays.sort(nums);
        List<List<Integer>> out = new ArrayList<>();
        List<Integer> local = new ArrayList<>();
        help(out,local,nums,0);
        return out;
    }

    private static void help(List<List<Integer>> out, List<Integer> local, int[] nums, int i) {
        out.add(new ArrayList<>(local));
        for (int j = i; j < nums.length; j++) {
            if (j==i || nums[j]!=nums[j-1]){
                local.add(nums[j]);
            }
            else{
                continue;//关键代码！
            }
            help(out,local,nums,j+1);
            local.remove(local.size()-1);
        }
    }
}

输出: