> For the complete documentation index, see [llms.txt](https://gl01.gitbook.io/gfg-editorials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl01.gitbook.io/gfg-editorials/2024/01-2024-jan-16/17-all-unique-permutations-of-an-array.md).

# 17 - All Unique Permutations of an array

#### 17. All Unique Permutations of an array

The problem can be found at the following link: [Question Link](https://www.geeksforgeeks.org/problems/all-unique-permutations-of-an-array/1)

![](https://badgen.net/badge/Level/Medium/yellow)

#### My Approach

* Sort the array in ascending order.
* Generate all unique permutations using `std::next_permutation`.
* Return the vector of unique permutations.

#### Time and Auxiliary Space Complexity

* **Time Complexity:** `O(N! * N)`, where N is the length of the array. This is because there are N! permutations, and for each permutation, it takes O(N) time to copy it.
* **Auxiliary Space Complexity:** `O(N!)`, where N is the length of the array. This is the space needed to store all unique permutations.

#### Code (C++)

```cpp
class Solution {
  public:
    vector<vector<int>> uniquePerms(vector<int> &arr, int n) {
        sort(arr.begin(), arr.end());

        vector<vector<int>> out;
        do {
            out.push_back(arr);
        } while (next_permutation(arr.begin(), arr.end()));

        return out;
    }
};
```

#### Contribution and Support

For discussions, questions, or doubts related to this solution, please visit our [discussion section](https://github.com/getlost01/gfg-potd/discussions). We welcome your input and aim to foster a collaborative learning environment.

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