Reformat the C# codes.

Disable creating new line before open brace.

codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs

@@ -9,23 +9,19 @@ using NUnit.Framework;
 
 namespace hello_algo.chapter_backtracking;
 
-public class preorder_traversal_iii_compact
-{
+public class preorder_traversal_iii_compact {
     static List<TreeNode> path;
     static List<List<TreeNode>> res;
 
     /* 前序遍历：例题三 */
-    static void preOrder(TreeNode root)
-    {
+    static void preOrder(TreeNode root) {
         // 剪枝
-        if (root == null || root.val == 3)
-        {
+        if (root == null || root.val == 3) {
             return;
         }
         // 尝试
         path.Add(root);
-        if (root.val == 7)
-        {
+        if (root.val == 7) {
             // 记录解
             res.Add(new List<TreeNode>(path));
         }
@@ -36,8 +32,7 @@ public class preorder_traversal_iii_compact
     }
 
     [Test]
-    public void Test()
-    {
+    public void Test() {
         TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
         Console.WriteLine("\n初始化二叉树");
         PrintUtil.PrintTree(root);
@@ -48,9 +43,8 @@ public class preorder_traversal_iii_compact
         preOrder(root);
 
         Console.WriteLine("\n输出所有根节点到节点 7 的路径，且路径中不包含值为 3 的节点");
-        foreach (List<TreeNode> path in res)
-        {
+        foreach (List<TreeNode> path in res) {
             PrintUtil.PrintList(path.Select(p => p.val).ToList());
         }
     }
-}
+}