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.

Solution:

This problem can be solved by backtrack approach.

public class Solution {
    public IList<IList<int>> Permute(int[] nums) {
        IList<IList<int>> res = new List<IList<int>>();
        Permute(nums,0,nums.Length-1, res);
        return res;
        
    }
    
    public static int[] swap(int[] nums , int i , int j)
    {
        int temp = 0;
        temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
        return nums;
    }
     public static void Permute(int[] nums,int left , int right, IList<IList<int>> res) {
        if(left == right)
        {
            List<int> temp = nums.ToList();
            res.Add(temp);
        }
         else
         {
             for(int i = left ; i <= right ; i++)
             {
                 nums =  swap(nums, left , i);
                 Permute(nums, left+1,right,res);
                 nums = swap(nums, left , i);
             }
         }   
    }
    
}