• Question
• Solution

Question

Given a collection of numbers that might contain duplicates, return all possible unique permutations.

For example,

[1,1,2] have the following unique permutations:

[
  [1,1,2],
  [1,2,1],
  [2,1,1]
]

Solution

Result: Accepted Time: 31 ms

Here should be some explanations.

class Solution {
public:
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        vector<vector<int>> ret;
        sort(nums.begin(),nums.end());
        do{
            ret.push_back(nums);
        }while(next_permutation(nums.begin(),nums.end()));
        return ret;
    }
};

Complexity Analytics

• Time Complexity: $O(n!)$
• Space Complexity: $O(n!)$