refactor: add/refactor method in include, simplified print code (#471)

codes/csharp/chapter_backtracking/backtrack_find_constrained_paths.cs

@@ -70,7 +70,7 @@ public class backtrack_find_constrained_paths
     [Test]
     public void Test()
     {
-        TreeNode root = TreeNode.ArrToTree(new int?[] { 1, 7, 3, 4, 5, 6, 7 });
+        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);
 
@@ -82,12 +82,7 @@ public class backtrack_find_constrained_paths
         Console.WriteLine("\n输出所有根节点到节点 7 的路径，要求路径中不包含值为 3 的节点");
         foreach (List<TreeNode> path in res)
         {
-            List<int> vals = new List<int>();
+            PrintUtil.PrintList(path.Select(p => p.val).ToList());
-            foreach (TreeNode node in path)
-            {
-                vals.Add(node.val);
-            }
-            Console.WriteLine(string.Join(" ", vals));
         }
     }
 }

codes/csharp/chapter_backtracking/preorder_find_constrained_paths.cs

@@ -38,7 +38,7 @@ public class preorder_find_constrained_paths
     [Test]
     public void Test()
     {
-        TreeNode root = TreeNode.ArrToTree(new int?[] { 1, 7, 3, 4, 5, 6, 7 });
+        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);
 
@@ -50,12 +50,7 @@ public class preorder_find_constrained_paths
         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)
         {
-            List<int> vals = new List<int>();
+            PrintUtil.PrintList(path.Select(p => p.val).ToList());
-            foreach (TreeNode node in path)
-            {
-                vals.Add(node.val);
-            }
-            Console.WriteLine(string.Join(" ", vals));
         }
     }
 }

codes/csharp/chapter_backtracking/preorder_find_nodes.cs

@@ -6,6 +6,7 @@
 
 using hello_algo.include;
 using NUnit.Framework;
+using System.IO;
 
 namespace hello_algo.chapter_backtracking;
 
@@ -32,7 +33,7 @@ public class preorder_find_nodes
     [Test]
     public void Test()
     {
-        TreeNode root = TreeNode.ArrToTree(new int?[] { 1, 7, 3, 4, 5, 6, 7 });
+        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);
 
@@ -41,11 +42,6 @@ public class preorder_find_nodes
         preOrder(root);
 
         Console.WriteLine("\n输出所有值为 7 的节点");
-        List<int> vals = new List<int>();
+        PrintUtil.PrintList(res.Select(p => p.val).ToList());
-        foreach (TreeNode node in res)
-        {
-            vals.Add(node.val);
-        }
-        Console.WriteLine(string.Join(" ", vals));
     }
 }

codes/csharp/chapter_backtracking/preorder_find_paths.cs

@@ -37,7 +37,7 @@ public class preorder_find_paths
     [Test]
     public void Test()
     {
-        TreeNode root = TreeNode.ArrToTree(new int?[] { 1, 7, 3, 4, 5, 6, 7 });
+        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);
 
@@ -49,12 +49,7 @@ public class preorder_find_paths
         Console.WriteLine("\n输出所有根节点到节点 7 的路径");
         foreach (List<TreeNode> path in res)
         {
-            List<int> vals = new List<int>();
+            PrintUtil.PrintList(path.Select(p => p.val).ToList());
-            foreach (TreeNode node in path)
-            {
-                vals.Add(node.val);
-            }
-            Console.WriteLine(string.Join(" ", vals));
         }
     }
 }

codes/csharp/chapter_computational_complexity/space_complexity.cs

@@ -50,7 +50,7 @@ public class space_complexity
             nodes.Add(new ListNode(i));
         }
         // 长度为 n 的哈希表占用 O(n) 空间
-        Dictionary<int, String> map = new();
+        Dictionary<int, string> map = new();
         for (int i = 0; i < n; i++)
         {
             map.Add(i, i.ToString());

codes/csharp/chapter_graph/graph_adjacency_list.cs

@@ -85,8 +85,8 @@ public class GraphAdjList
         {
             List<int> tmp = new List<int>();
             foreach (Vertex vertex in entry.Value)
-                tmp.Add(vertex.Val);
+                tmp.Add(vertex.val);
-            Console.WriteLine(entry.Key.Val + ": [" + string.Join(", ", tmp) + "],");
+            Console.WriteLine(entry.Key.val + ": [" + string.Join(", ", tmp) + "],");
         }
     }
 }
@@ -97,7 +97,7 @@ public class graph_adjacency_list
     public void Test()
     {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.valsToVets(new int[] { 1, 3, 2, 5, 4 });
+        Vertex[] v = Vertex.ValsToVets(new int[] { 1, 3, 2, 5, 4 });
         Vertex[][] edges = new Vertex[][] { new Vertex[] { v[0], v[1] }, new Vertex[] { v[0], v[3] },
                                             new Vertex[] { v[1], v[2] }, new Vertex[] { v[2], v[3] },
                                             new Vertex[] { v[2], v[4] }, new Vertex[] { v[3], v[4] } };

codes/csharp/chapter_graph/graph_adjacency_matrix.cs

@@ -104,7 +104,7 @@ class GraphAdjMat
         Console.Write("顶点列表 = ");
         PrintUtil.PrintList(vertices);
         Console.WriteLine("邻接矩阵 =");
-        PrintUtil.printMatrix(adjMat);
+        PrintUtil.PrintMatrix(adjMat);
     }
 }
 

codes/csharp/chapter_graph/graph_bfs.cs

@@ -46,7 +46,7 @@ public class graph_bfs
     public void Test()
     {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.valsToVets(new int[10] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
+        Vertex[] v = Vertex.ValsToVets(new int[10] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
         Vertex[][] edges = new Vertex[12][]
         {
             new Vertex[2] { v[0], v[1] }, new Vertex[2] { v[0], v[3] }, new Vertex[2] { v[1], v[2] },
@@ -62,6 +62,6 @@ public class graph_bfs
         /* 广度优先遍历 BFS */
         List<Vertex> res = graphBFS(graph, v[0]);
         Console.WriteLine("\n广度优先遍历（BFS）顶点序列为");
-        Console.WriteLine(string.Join(" ", Vertex.vetsToVals(res)));
+        Console.WriteLine(string.Join(" ", Vertex.VetsToVals(res)));
     }
 }

codes/csharp/chapter_graph/graph_dfs.cs

@@ -44,7 +44,7 @@ public class graph_dfs
     public void Test()
     {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.valsToVets(new int[7] { 0, 1, 2, 3, 4, 5, 6 });
+        Vertex[] v = Vertex.ValsToVets(new int[7] { 0, 1, 2, 3, 4, 5, 6 });
         Vertex[][] edges = new Vertex[6][]
         {
             new Vertex[2] { v[0], v[1] }, new Vertex[2] { v[0], v[3] }, new Vertex[2] { v[1], v[2] },
@@ -58,6 +58,6 @@ public class graph_dfs
         /* 深度优先遍历 DFS */
         List<Vertex> res = graphDFS(graph, v[0]);
         Console.WriteLine("\n深度优先遍历（DFS）顶点序列为");
-        Console.WriteLine(string.Join(" ", Vertex.vetsToVals(res)));
+        Console.WriteLine(string.Join(" ", Vertex.VetsToVals(res)));
     }
 }

codes/csharp/chapter_hashing/array_hash_map.cs

@@ -8,12 +8,12 @@ using NUnit.Framework;
 
 namespace hello_algo.chapter_hashing;
 
-/* 键值对 int->String */
+/* 键值对 int->string */
 class Entry
 {
     public int key;
-    public String val;
+    public string val;
-    public Entry(int key, String val)
+    public Entry(int key, string val)
     {
         this.key = key;
         this.val = val;
@@ -42,7 +42,7 @@ class ArrayHashMap
     }
 
     /* 查询操作 */
-    public String? get(int key)
+    public string? get(int key)
     {
         int index = hashFunc(key);
         Entry? pair = buckets[index];
@@ -51,7 +51,7 @@ class ArrayHashMap
     }
 
     /* 添加操作 */
-    public void put(int key, String val)
+    public void put(int key, string val)
     {
         Entry pair = new Entry(key, val);
         int index = hashFunc(key);
@@ -91,9 +91,9 @@ class ArrayHashMap
     }
 
     /* 获取所有值 */
-    public List<String> valueSet()
+    public List<string> valueSet()
     {
-        List<String> valueSet = new();
+        List<string> valueSet = new();
         foreach (Entry? pair in buckets)
         {
             if (pair != null)
@@ -133,7 +133,7 @@ public class array_hash_map
 
         /* 查询操作 */
         // 向哈希表输入键 key ，得到值 value
-        String? name = map.get(15937);
+        string? name = map.get(15937);
         Console.WriteLine("\n输入学号 15937 ，查询到姓名 " + name);
 
         /* 删除操作 */
@@ -154,7 +154,7 @@ public class array_hash_map
             Console.WriteLine(key);
         }
         Console.WriteLine("\n单独遍历值 Value");
-        foreach (String val in map.valueSet())
+        foreach (string val in map.valueSet())
         {
             Console.WriteLine(val);
         }

codes/csharp/chapter_hashing/hash_map.cs

@@ -16,7 +16,7 @@ public class hash_map
     public void Test()
     {
         /* 初始化哈希表 */
-        Dictionary<int, String> map = new();
+        Dictionary<int, string> map = new();
 
         /* 添加操作 */
         // 在哈希表中添加键值对 (key, value)
@@ -26,18 +26,18 @@ public class hash_map
         map.Add(13276, "小法");
         map.Add(10583, "小鸭");
         Console.WriteLine("\n添加完成后，哈希表为\nKey -> Value");
-        PrintUtil.printHashMap(map);
+        PrintUtil.PrintHashMap(map);
 
         /* 查询操作 */
         // 向哈希表输入键 key ，得到值 value
-        String name = map[15937];
+        string name = map[15937];
         Console.WriteLine("\n输入学号 15937 ，查询到姓名 " + name);
 
         /* 删除操作 */
         // 在哈希表中删除键值对 (key, value)
         map.Remove(10583);
         Console.WriteLine("\n删除 10583 后，哈希表为\nKey -> Value");
-        PrintUtil.printHashMap(map);
+        PrintUtil.PrintHashMap(map);
 
         /* 遍历哈希表 */
         Console.WriteLine("\n遍历键值对 Key->Value");
@@ -51,7 +51,7 @@ public class hash_map
             Console.WriteLine(key);
         }
         Console.WriteLine("\n单独遍历值 Value");
-        foreach (String val in map.Values)
+        foreach (string val in map.Values)
         {
             Console.WriteLine(val);
         }

codes/csharp/chapter_heap/heap.cs

@@ -15,14 +15,14 @@ public class heap
     {
         heap.Enqueue(val, val); // 元素入堆
         Console.WriteLine($"\n元素 {val} 入堆后\n");
-        PrintUtil.printHeap(heap);
+        PrintUtil.PrintHeap(heap);
     }
 
     public void testPop(PriorityQueue<int, int> heap)
     {
         int val = heap.Dequeue(); // 堆顶元素出堆
         Console.WriteLine($"\n堆顶元素 {val} 出堆后\n");
-        PrintUtil.printHeap(heap);
+        PrintUtil.PrintHeap(heap);
     }
     [Test]
     public void Test()
@@ -65,6 +65,6 @@ public class heap
         var list = new int[] { 1, 3, 2, 5, 4 };
         minHeap = new PriorityQueue<int, int>(list.Select(x => (x, x)));
         Console.WriteLine("输入列表并建立小顶堆后");
-        PrintUtil.printHeap(minHeap);
+        PrintUtil.PrintHeap(minHeap);
     }
 }

codes/csharp/chapter_heap/my_heap.cs

@@ -143,7 +143,7 @@ class MaxHeap
     public void print()
     {
         var queue = new Queue<int>(maxHeap);
-        PrintUtil.printHeap(queue);
+        PrintUtil.PrintHeap(queue);
     }
 }
 

codes/csharp/chapter_stack_and_queue/array_stack.cs

@@ -75,7 +75,7 @@ public class array_stack
         stack.push(2);
         stack.push(5);
         stack.push(4);
-        Console.WriteLine("栈 stack = " + String.Join(",", stack.toArray()));
+        Console.WriteLine("栈 stack = " + string.Join(",", stack.toArray()));
 
         /* 访问栈顶元素 */
         int peek = stack.peek();
@@ -83,7 +83,7 @@ public class array_stack
 
         /* 元素出栈 */
         int pop = stack.pop();
-        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + String.Join(",", stack.toArray()));
+        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + string.Join(",", stack.toArray()));
 
         /* 获取栈的长度 */
         int size = stack.size();

codes/csharp/chapter_stack_and_queue/deque.cs

@@ -23,7 +23,7 @@ public class deque
         deque.AddLast(4);
         deque.AddFirst(3);  // 添加至队首
         deque.AddFirst(1);
-        Console.WriteLine("双向队列 deque = " + String.Join(",", deque.ToArray()));
+        Console.WriteLine("双向队列 deque = " + string.Join(",", deque));
 
         /* 访问元素 */
         int peekFirst = deque.First.Value;  // 队首元素
@@ -33,9 +33,9 @@ public class deque
 
         /* 元素出队 */
         deque.RemoveFirst();  // 队首元素出队
-        Console.WriteLine("队首元素出队后 deque = " + String.Join(",", deque.ToArray()));
+        Console.WriteLine("队首元素出队后 deque = " + string.Join(",", deque));
         deque.RemoveLast();   // 队尾元素出队
-        Console.WriteLine("队尾元素出队后 deque = " + String.Join(",", deque.ToArray()));
+        Console.WriteLine("队尾元素出队后 deque = " + string.Join(",", deque));
 
         /* 获取双向队列的长度 */
         int size = deque.Count;

codes/csharp/chapter_stack_and_queue/linkedlist_queue.cs

@@ -102,7 +102,7 @@ public class linkedlist_queue
         queue.push(2);
         queue.push(5);
         queue.push(4);
-        Console.WriteLine("队列 queue = " + String.Join(",", queue.toArray()));
+        Console.WriteLine("队列 queue = " + string.Join(",", queue.toArray()));
 
         /* 访问队首元素 */
         int peek = queue.peek();
@@ -110,7 +110,7 @@ public class linkedlist_queue
 
         /* 元素出队 */
         int pop = queue.pop();
-        Console.WriteLine("出队元素 pop = " + pop + "，出队后 queue = " + String.Join(",", queue.toArray()));
+        Console.WriteLine("出队元素 pop = " + pop + "，出队后 queue = " + string.Join(",", queue.toArray()));
 
         /* 获取队列的长度 */
         int size = queue.size();

codes/csharp/chapter_stack_and_queue/linkedlist_stack.cs

@@ -92,7 +92,7 @@ public class linkedlist_stack
         stack.push(2);
         stack.push(5);
         stack.push(4);
-        Console.WriteLine("栈 stack = " + String.Join(",", stack.toArray()));
+        Console.WriteLine("栈 stack = " + string.Join(",", stack.toArray()));
 
         /* 访问栈顶元素 */
         int peek = stack.peek();
@@ -100,7 +100,7 @@ public class linkedlist_stack
 
         /* 元素出栈 */
         int pop = stack.pop();
-        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + String.Join(",", stack.toArray()));
+        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + string.Join(",", stack.toArray()));
 
         /* 获取栈的长度 */
         int size = stack.size();

codes/csharp/chapter_stack_and_queue/queue.cs

@@ -22,7 +22,7 @@ public class queue
         queue.Enqueue(2);
         queue.Enqueue(5);
         queue.Enqueue(4);
-        Console.WriteLine("队列 queue = " + String.Join(",", queue.ToArray()));
+        Console.WriteLine("队列 queue = " + string.Join(",", queue));
 
         /* 访问队首元素 */
         int peek = queue.Peek();
@@ -30,7 +30,7 @@ public class queue
 
         /* 元素出队 */
         int pop = queue.Dequeue();
-        Console.WriteLine("出队元素 pop = " + pop + "，出队后 queue = " + String.Join(",", queue.ToArray()));
+        Console.WriteLine("出队元素 pop = " + pop + "，出队后 queue = " + string.Join(",", queue));
 
         /* 获取队列的长度 */
         int size = queue.Count();

codes/csharp/chapter_stack_and_queue/stack.cs

@@ -23,7 +23,7 @@ public class stack
         stack.Push(5);
         stack.Push(4);
         // 请注意，stack.ToArray() 得到的是倒序序列，即索引 0 为栈顶
-        Console.WriteLine("栈 stack = " + string.Join(",", stack.ToArray()));
+        Console.WriteLine("栈 stack = " + string.Join(",", stack));
 
         /* 访问栈顶元素 */
         int peek = stack.Peek();
@@ -31,7 +31,7 @@ public class stack
 
         /* 元素出栈 */
         int pop = stack.Pop();
-        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + string.Join(",", stack.ToArray()));
+        Console.WriteLine("出栈元素 pop = " + pop + "，出栈后 stack = " + string.Join(",", stack));
 
         /* 获取栈的长度 */
         int size = stack.Count();

codes/csharp/chapter_tree/binary_tree_bfs.cs

@@ -37,11 +37,11 @@ public class binary_tree_bfs
     {
         /* 初始化二叉树 */
         // 这里借助了一个从数组直接生成二叉树的函数
-        TreeNode? root = TreeNode.ArrToTree(new int?[] { 1, 2, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });
         Console.WriteLine("\n初始化二叉树\n");
         PrintUtil.PrintTree(root);
 
         List<int> list = levelOrder(root);
-        Console.WriteLine("\n层序遍历的节点打印序列 = " + string.Join(",", list.ToArray()));
+        Console.WriteLine("\n层序遍历的节点打印序列 = " + string.Join(",", list));
     }
 }

codes/csharp/chapter_tree/binary_tree_dfs.cs

@@ -48,20 +48,20 @@ public class binary_tree_dfs
     {
         /* 初始化二叉树 */
         // 这里借助了一个从数组直接生成二叉树的函数
-        TreeNode? root = TreeNode.ArrToTree(new int?[] { 1, 2, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });
         Console.WriteLine("\n初始化二叉树\n");
         PrintUtil.PrintTree(root);
 
         list.Clear();
         preOrder(root);
-        Console.WriteLine("\n前序遍历的节点打印序列 = " + string.Join(",", list.ToArray()));
+        Console.WriteLine("\n前序遍历的节点打印序列 = " + string.Join(",", list));
 
         list.Clear();
         inOrder(root);
-        Console.WriteLine("\n中序遍历的节点打印序列 = " + string.Join(",", list.ToArray()));
+        Console.WriteLine("\n中序遍历的节点打印序列 = " + string.Join(",", list));
 
         list.Clear();
         postOrder(root);
-        Console.WriteLine("\n后序遍历的节点打印序列 = " + string.Join(",", list.ToArray()));
+        Console.WriteLine("\n后序遍历的节点打印序列 = " + string.Join(",", list));
     }
 }

codes/csharp/include/PrintUtil.cs

@@ -9,9 +9,9 @@ namespace hello_algo.include;
 public class Trunk
 {
     public Trunk? prev;
-    public String str;
+    public string str;
 
-    public Trunk(Trunk? prev, String str)
+    public Trunk(Trunk? prev, string str)
     {
         this.prev = prev;
         this.str = str;
@@ -24,24 +24,46 @@ public class PrintUtil
      * Print a list
      * @param list
      */
-    public static void PrintList(List<int> list)
+    public static void PrintList<T>(List<T> list)
     {
         Console.WriteLine("[" + string.Join(", ", list) + "]");
     }
 
+    /* Print a matrix (Array) */
+    public static void PrintMatrix<T>(T[][] matrix)
+    {
+        Console.WriteLine("[");
+        foreach (T[] row in matrix)
+        {
+            Console.WriteLine("  " + string.Join(", ", row) + ",");
+        }
+        Console.WriteLine("]");
+    }
+
+    /* Print a matrix (List) */
+    public static void PrintMatrix<T>(List<List<T>> matrix)
+    {
+        Console.WriteLine("[");
+        foreach (List<T> row in matrix)
+        {
+            Console.WriteLine("  " + string.Join(", ", row) + ",");
+        }
+        Console.WriteLine("]");
+    }
+
     /**
      * Print a linked list
      * @param head
      */
     public static void PrintLinkedList(ListNode head)
     {
-        List<String> list = new();
+        List<string> list = new();
         while (head != null)
         {
             list.Add(head.val.ToString());
             head = head.next;
         }
-        Console.Write(String.Join(" -> ", list));
+        Console.Write(string.Join(" -> ", list));
     }
 
     /**
@@ -68,7 +90,7 @@ public class PrintUtil
             return;
         }
 
-        String prev_str = "    ";
+        string prev_str = "    ";
         Trunk trunk = new Trunk(prev, prev_str);
 
         PrintTree(root.right, trunk, true);
@@ -88,7 +110,7 @@ public class PrintUtil
             prev.str = prev_str;
         }
 
-        showTrunks(trunk);
+        ShowTrunks(trunk);
         Console.WriteLine(" " + root.val);
 
         if (prev != null)
@@ -104,14 +126,14 @@ public class PrintUtil
      * Helper function to print branches of the binary tree
      * @param p
      */
-    public static void showTrunks(Trunk? p)
+    public static void ShowTrunks(Trunk? p)
     {
         if (p == null)
         {
             return;
         }
 
-        showTrunks(p.prev);
+        ShowTrunks(p.prev);
         Console.Write(p.str);
     }
 
@@ -121,7 +143,7 @@ public class PrintUtil
      * @param <V>
      * @param map
      */
-    public static void printHashMap<K, V>(Dictionary<K, V> map) where K : notnull
+    public static void PrintHashMap<K, V>(Dictionary<K, V> map) where K : notnull
     {
         foreach (var kv in map.Keys)
         {
@@ -129,17 +151,17 @@ public class PrintUtil
         }
     }
 
-    public static void printHeap(Queue<int> queue)
+    public static void PrintHeap(Queue<int> queue)
     {
         Console.Write("堆的数组表示：");
         List<int> list = queue.ToList();
         Console.WriteLine(string.Join(',', list));
         Console.WriteLine("堆的树状表示：");
-        TreeNode tree = TreeNode.ArrToTree(list.Cast<int?>().ToArray());
+        TreeNode tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
         PrintTree(tree);
     }
 
-    public static void printHeap(PriorityQueue<int, int> queue)
+    public static void PrintHeap(PriorityQueue<int, int> queue)
     {
         var newQueue = new PriorityQueue<int, int>(queue.UnorderedItems, queue.Comparer);
         Console.Write("堆的数组表示：");    
@@ -150,17 +172,7 @@ public class PrintUtil
         }
         Console.WriteLine("堆的树状表示：");
         Console.WriteLine(string.Join(',', list.ToList()));
-        TreeNode tree = TreeNode.ArrToTree(list.Cast<int?>().ToArray());
+        TreeNode tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
         PrintTree(tree);
     }
-
-    public static void printMatrix(List<List<int>> matrix)
-    {
-        Console.WriteLine("[");
-        foreach (List<int> row in matrix)
-        {
-            Console.WriteLine("  [" + string.Join(", ", row.Select(r => $"{r}")) + "],");
-        }
-        Console.WriteLine("]");
-    }
 }

codes/csharp/include/TreeNode.cs

@@ -23,25 +23,25 @@ public class TreeNode
      * @param arr
      * @return
      */
-    public static TreeNode? ArrToTree(int?[] arr)
+    public static TreeNode? ListToTree(List<int?> arr)
     {
-        if (arr.Length == 0 || arr[0] == null)
+        if (arr.Count == 0 || arr[0] == null)
             return null;
 
-        TreeNode root = new TreeNode((int)arr[0]);
+        TreeNode root = new TreeNode(arr[0]!.Value);
         Queue<TreeNode> queue = new Queue<TreeNode>();
         queue.Enqueue(root);
         int i = 0;
         while (queue.Count != 0)
         {
             TreeNode node = queue.Dequeue();
-            if (++i >= arr.Length) break;
+            if (++i >= arr.Count) break;
             if (arr[i] != null)
             {
                 node.left = new TreeNode((int)arr[i]);
                 queue.Enqueue(node.left);
             }
-            if (++i >= arr.Length) break;
+            if (++i >= arr.Count) break;
             if (arr[i] != null)
             {
                 node.right = new TreeNode((int)arr[i]);
@@ -92,6 +92,6 @@ public class TreeNode
             return root;
         TreeNode? left = GetTreeNode(root.left, val);
         TreeNode? right = GetTreeNode(root.right, val);
-        return left != null ? left : right;
+        return left ?? right;
     }
 }

codes/csharp/include/Vertex.cs

@@ -9,14 +9,14 @@ namespace hello_algo.include;
 /* 顶点类 */
 public class Vertex
 {
-    public int Val { get; init; }
+    public int val;
     public Vertex(int val)
     {
-        Val = val;
+        this.val = val;
     }
 
     /* 输入值列表 vals ，返回顶点列表 vets */
-    public static Vertex[] valsToVets(int[] vals)
+    public static Vertex[] ValsToVets(int[] vals)
     {
         Vertex[] vets = new Vertex[vals.Length];
         for (int i = 0; i < vals.Length; i++)
@@ -27,12 +27,12 @@ public class Vertex
     }
 
     /* 输入顶点列表 vets ，返回值列表 vals */
-    public static List<int> vetsToVals(List<Vertex> vets)
+    public static List<int> VetsToVals(List<Vertex> vets)
     {
         List<int> vals = new List<int>();
         foreach (Vertex vet in vets)
         {
-            vals.Add(vet.Val);
+            vals.Add(vet.val);
         }
         return vals;
     }