Update0046.全排列，添加C#

problems/0046.全排列.md

@@ -486,6 +486,37 @@ object Solution {
   }
 }
 ```
+### C#
+```csharp
+public class Solution
+{
+    public IList<IList<int>> res = new List<IList<int>>();
+    public IList<int> path = new List<int>();
+    public IList<IList<int>> Permute(int[] nums)
+    {
+        var used = new bool[nums.Length];
+        BackTracking(nums, used);
+        return res;
+    }
+    public void BackTracking(int[] nums, bool[] used)
+    {
+        if (path.Count == nums.Length)
+        {
+            res.Add(new List<int>(path));
+            return;
+        }
+        for (int i = 0; i < nums.Length; i++)
+        {
+            if (used[i]) continue;
+            used[i] = true;
+            path.Add(nums[i]);
+            BackTracking(nums, used);
+            used[i] = false;
+            path.RemoveAt(path.Count - 1);
+        }
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">