Leetcode090-subsetsII

Description

Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

Example

Input: [1,2,2]
Output:
[
  [2],
  [1],
  [1,2,2],
  [2,2],
  [1,2],
  []
]

Solution

class Solution {
    public void backtrack(List<List<Integer>> res, List<Integer> temp, int[] nums, int start){
        res.add(new ArrayList<Integer>(temp));
        for (int i = start; i < nums.length; i++){
            if (i > start && nums[i] == nums[i-1]) continue;
            temp.add(nums[i]);
            backtrack(res, temp, nums, i+1);
            temp.remove(temp.size()-1);
        }
    }
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> res = new ArrayList<>();
        Arrays.sort(nums);
        backtrack(res, new ArrayList<Integer>(), nums, 0);
        return res;
    }
}

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