Day i do not know

46. Permutations/Solution.cs

@@ -0,0 +1,30 @@
+namespace _46._Permutations;
+
+public class Solution
+{
+    public IList<IList<int>> Permute(int[] nums)
+    {
+        List<IList<int>> l = new List<IList<int>>();
+        Recursion(l, new List<int>(), nums.ToHashSet());
+        return l;
+    }
+
+    private void Recursion(List<IList<int>> result, List<int> cur, HashSet<int> aviable)
+    {
+        if(aviable.Count == 0)
+        {
+            result.Add(cur);
+            return;
+        }
+
+        foreach(var av in aviable)
+        {
+            var newAviable = aviable.ToHashSet();
+            newAviable.Remove(av);
+
+            var newCur = cur.ToList();
+            newCur.Add(av);
+            Recursion(result, newCur, newAviable);
+        }
+    }
+}