46. Permutations | Leetcode Solution

 46. Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

 

Example 1:

Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Example 2:

Input: nums = [0,1]
Output: [[0,1],[1,0]]

Example 3:

Input: nums = [1]
Output: [[1]]

 

Constraints:

• 1 <= nums.length <= 6
• -10 <= nums[i] <= 10
• All the integers of nums are unique.

The solution to the above question is-

class Solution

{

public:

  vector<vector<int>> ans;

  void helper(vector<int> &nums, int l)

  {

    if (l >= nums.size())

    {

      ans.push_back(nums);

      return;

    }

    for (int i = l; i < nums.size(); i++)

    {

      swap(nums[l], nums[i]);

      helper(nums, l + 1);

      swap(nums[l], nums[i]);

    }

  }

  vector<vector<int>> permute(vector<int> &nums)

  {

    helper(nums, 0);

    return ans;

  }

};