Add kotlin code for chapter_stack_and_queue and chapter_tree (#1197)

* Add kotlin code block for chapter_hashing

* Add kotlin code block for chapter_heap.

* Add kotlin code block for chapter_stack_and_queue and chapter_tree

* fix indentation

* Update binary_tree.md

---------

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

docs/chapter_stack_and_queue/deque.md

@@ -327,7 +327,29 @@
 === "Kotlin"
 
     ```kotlin title="deque.kt"
-
+    /* 初始化双向队列 */
+    val deque = LinkedList<Int>()
+    
+    /* 元素入队 */
+    deque.offerLast(2)  // 添加至队尾
+    deque.offerLast(5)
+    deque.offerLast(4)
+    deque.offerFirst(3) // 添加至队首
+    deque.offerFirst(1)
+    
+    /* 访问元素 */
+    val peekFirst = deque.peekFirst() // 队首元素
+    val peekLast = deque.peekLast()   // 队尾元素
+    
+    /* 元素出队 */
+    val popFirst = deque.pollFirst() // 队首元素出队
+    val popLast = deque.pollLast()   // 队尾元素出队
+    
+    /* 获取双向队列的长度 */
+    val size = deque.size
+    
+    /* 判断双向队列是否为空 */
+    val isEmpty = deque.isEmpty()
     ```
 
 === "Zig"

docs/chapter_stack_and_queue/queue.md

@@ -305,7 +305,27 @@
 === "Kotlin"
 
     ```kotlin title="queue.kt"
-
+    /* 初始化队列 */
+    val queue = LinkedList<Int>()
+    
+    /* 元素入队 */
+    queue.offer(1)
+    queue.offer(3)
+    queue.offer(2)
+    queue.offer(5)
+    queue.offer(4)
+    
+    /* 访问队首元素 */
+    val peek = queue.peek()
+    
+    /* 元素出队 */
+    val pop = queue.poll()
+    
+    /* 获取队列的长度 */
+    val size = queue.size
+    
+    /* 判断队列是否为空 */
+    val isEmpty = queue.isEmpty()
     ```
 
 === "Zig"

docs/chapter_stack_and_queue/stack.md

@@ -299,7 +299,27 @@
 === "Kotlin"
 
     ```kotlin title="stack.kt"
-
+    /* 初始化栈 */
+    val stack = Stack<Int>()
+    
+    /* 元素入栈 */
+    stack.push(1)
+    stack.push(3)
+    stack.push(2)
+    stack.push(5)
+    stack.push(4)
+    
+    /* 访问栈顶元素 */
+    val peek = stack.peek()
+    
+    /* 元素出栈 */
+    val pop = stack.pop()
+    
+    /* 获取栈的长度 */
+    val size = stack.size
+    
+    /* 判断是否为空 */
+    val isEmpty = stack.isEmpty()
     ```
 
 === "Zig"