fix(csharp): reformat csharp codes and docs (#652)

* fix(csharp): reformat the C# codes and docs

* Update time_complexity.md

---------

Co-authored-by: Yudong Jin <krahets@163.com>

codes/csharp/chapter_array_and_linkedlist/list.cs

@@ -45,7 +45,7 @@ public class list {
 
         /* 通过索引遍历列表 */
         int count = 0;
-        for (int i = 0; i < list.Count(); i++) {
+        for (int i = 0; i < list.Count; i++) {
             count++;
         }
 

codes/csharp/chapter_array_and_linkedlist/my_list.cs

@@ -87,7 +87,7 @@ class MyList {
     /* 列表扩容 */
     public void extendCapacity() {
         // 新建一个长度为 numsCapacity * extendRatio 的数组，并将原数组拷贝到新数组
-        System.Array.Resize(ref nums, numsCapacity * extendRatio);
+        Array.Resize(ref nums, numsCapacity * extendRatio);
         // 更新列表容量
         numsCapacity = nums.Length;
     }

codes/csharp/chapter_computational_complexity/time_complexity.cs

@@ -87,9 +87,7 @@ public class time_complexity {
             for (int j = 0; j < i; j++) {
                 if (nums[j] > nums[j + 1]) {
                     // 交换 nums[j] 与 nums[j + 1]
-                    int tmp = nums[j];
-                    nums[j] = nums[j + 1];
-                    nums[j + 1] = tmp;
+                    (nums[j + 1], nums[j]) = (nums[j], nums[j + 1]);
                     count += 3;  // 元素交换包含 3 个单元操作
                 }
             }

codes/csharp/chapter_searching/two_sum.cs

@@ -17,7 +17,7 @@ public class two_sum {
                     return new int[] { i, j };
             }
         }
-        return new int[0];
+        return Array.Empty<int>();
     }
 
     /* 方法二：辅助哈希表 */
@@ -32,7 +32,7 @@ public class two_sum {
             }
             dic.Add(nums[i], i);
         }
-        return new int[0];
+        return Array.Empty<int>();
     }
 
     [Test]

codes/csharp/chapter_stack_and_queue/queue.cs

@@ -29,11 +29,11 @@ public class queue {
         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();
+        int size = queue.Count;
         Console.WriteLine("队列长度 size = " + size);
 
         /* 判断队列是否为空 */
-        bool isEmpty = queue.Count() == 0;
+        bool isEmpty = queue.Count == 0;
         Console.WriteLine("队列是否为空 = " + isEmpty);
     }
 }

codes/csharp/chapter_stack_and_queue/stack.cs

@@ -30,11 +30,11 @@ public class stack {
         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();
+        int size = stack.Count;
         Console.WriteLine("栈的长度 size = " + size);
 
         /* 判断是否为空 */
-        bool isEmpty = stack.Count() == 0;
+        bool isEmpty = stack.Count == 0;
         Console.WriteLine("栈是否为空 = " + isEmpty);
     }
 }