LeetCode | 90. Subsets II

 

題目：

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],
  []
]

 

代碼：

class Solution {
public:
    void backSubsets(vector<vector<int>>& res, vector<int>& nums, vector<int> cur, int idx, const int& length) {
        
        if(idx == length)
            return;
        // cout << idx << ' ' << length << endl;
        for(int i = idx; i<length; i++)
        {
            
            // if(i == idx || i == length - 1 || (i < length - 1 && nums[i] != nums[i+1]))
            if(i == idx || i > idx && nums[i] != nums[i - 1])
            {
                cur.push_back(nums[i]);
                res.push_back(cur);
                backSubsets(res, nums, cur, i+1, length);
                cur.pop_back();
            }
        }
        return;
    }
    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        vector<vector<int>> res;
        sort(nums.begin(), nums.end());
        int length = nums.size();
        vector<int> cur;
        res.push_back(cur);
        backSubsets(res, nums, cur, 0, length);
        return res;
    }
};