diff --git a/codes/c/chapter_heap/my_heap.c b/codes/c/chapter_heap/my_heap.c
index a6f4e8342..308a3cf1c 100644
--- a/codes/c/chapter_heap/my_heap.c
+++ b/codes/c/chapter_heap/my_heap.c
@@ -52,7 +52,7 @@ int right(MaxHeap *maxHeap, int i) {
 
 /* 获取父节点的索引 */
 int parent(MaxHeap *maxHeap, int i) {
-    return (i - 1) / 2;
+    return (i - 1) / 2; // 向下取整
 }
 
 /* 交换元素 */
diff --git a/codes/kotlin/chapter_array_and_linkedlist/linked_list.kt b/codes/kotlin/chapter_array_and_linkedlist/linked_list.kt
index 8431e08dc..15b3ee4aa 100644
--- a/codes/kotlin/chapter_array_and_linkedlist/linked_list.kt
+++ b/codes/kotlin/chapter_array_and_linkedlist/linked_list.kt
@@ -20,6 +20,7 @@ fun insert(n0: ListNode?, p: ListNode?) {
 fun remove(n0: ListNode?) {
     if (n0?.next == null)
         return
+    // n0 -> P -> n1
     val p = n0.next
     val n1 = p?.next
     n0.next = n1
@@ -78,10 +79,10 @@ fun main() {
     printLinkedList(n0)
 
     /* 访问节点 */
-    val node: ListNode = access(n0, 3)!!
+    val node = access(n0, 3)!!
     println("链表中索引 3 处的节点的值 = ${node._val}")
 
     /* 查找节点 */
-    val index: Int = find(n0, 2)
+    val index = find(n0, 2)
     println("链表中值为 2 的节点的索引 = $index")
 }
\ No newline at end of file
diff --git a/codes/kotlin/chapter_computational_complexity/recursion.kt b/codes/kotlin/chapter_computational_complexity/recursion.kt
index 1d89b7606..0b7ac65a8 100644
--- a/codes/kotlin/chapter_computational_complexity/recursion.kt
+++ b/codes/kotlin/chapter_computational_complexity/recursion.kt
@@ -26,6 +26,7 @@ fun forLoopRecur(n: Int): Int {
     var res = 0
     // 递: 递归调用
     for (i in n downTo 0) {
+        // 通过“入栈操作”模拟“递”
         stack.push(i)
     }
     // 归: 返回结果
diff --git a/codes/kotlin/chapter_computational_complexity/time_complexity.kt b/codes/kotlin/chapter_computational_complexity/time_complexity.kt
index 534cf2854..0c4c98a7d 100644
--- a/codes/kotlin/chapter_computational_complexity/time_complexity.kt
+++ b/codes/kotlin/chapter_computational_complexity/time_complexity.kt
@@ -18,7 +18,6 @@ fun constant(n: Int): Int {
 /* 线性阶 */
 fun linear(n: Int): Int {
     var count = 0
-    // 循环次数与数组长度成正比
     for (i in 0..<n)
         count++
     return count
@@ -55,7 +54,9 @@ fun bubbleSort(nums: IntArray): Int {
         for (j in 0..<i) {
             if (nums[j] > nums[j + 1]) {
                 // 交换 nums[j] 与 nums[j + 1]
-                nums[j] = nums[j + 1].also { nums[j + 1] = nums[j] }
+                val temp = nums[j]
+                nums[j] = nums[j + 1]
+                nums[j + 1] = temp
                 count += 3 // 元素交换包含 3 个单元操作
             }
         }
@@ -66,8 +67,8 @@ fun bubbleSort(nums: IntArray): Int {
 /* 指数阶（循环实现） */
 fun exponential(n: Int): Int {
     var count = 0
-    // 细胞每轮一分为二，形成数列 1, 2, 4, 8, ..., 2^(n-1)
     var base = 1
+    // 细胞每轮一分为二，形成数列 1, 2, 4, 8, ..., 2^(n-1)
     for (i in 0..<n) {
         for (j in 0..<base) {
             count++
diff --git a/codes/kotlin/chapter_computational_complexity/worst_best_time_complexity.kt b/codes/kotlin/chapter_computational_complexity/worst_best_time_complexity.kt
index 94a9cb558..d51e7a4b2 100644
--- a/codes/kotlin/chapter_computational_complexity/worst_best_time_complexity.kt
+++ b/codes/kotlin/chapter_computational_complexity/worst_best_time_complexity.kt
@@ -13,12 +13,11 @@ fun randomNumbers(n: Int): Array<Int?> {
     for (i in 0..<n) {
         nums[i] = i + 1
     }
-    val mutableList = nums.toMutableList()
     // 随机打乱数组元素
-    mutableList.shuffle()
+    nums.shuffle()
     val res = arrayOfNulls<Int>(n)
     for (i in 0..<n) {
-        res[i] = mutableList[i]
+        res[i] = nums[i]
     }
     return res
 }
diff --git a/codes/kotlin/chapter_dynamic_programming/climbing_stairs_dp.kt b/codes/kotlin/chapter_dynamic_programming/climbing_stairs_dp.kt
index 833085de5..5a029a30e 100644
--- a/codes/kotlin/chapter_dynamic_programming/climbing_stairs_dp.kt
+++ b/codes/kotlin/chapter_dynamic_programming/climbing_stairs_dp.kt
@@ -27,7 +27,9 @@ fun climbingStairsDPComp(n: Int): Int {
     var a = 1
     var b = 2
     for (i in 3..n) {
-        b += a.also { a = b }
+        val temp = b
+        b += a
+        a = temp
     }
     return b
 }
diff --git a/codes/kotlin/chapter_dynamic_programming/knapsack.kt b/codes/kotlin/chapter_dynamic_programming/knapsack.kt
index 868beab1f..be7225f09 100644
--- a/codes/kotlin/chapter_dynamic_programming/knapsack.kt
+++ b/codes/kotlin/chapter_dynamic_programming/knapsack.kt
@@ -59,11 +59,7 @@ fun knapsackDFSMem(
 }
 
 /* 0-1 背包：动态规划 */
-fun knapsackDP(
-    wgt: IntArray,
-    _val: IntArray,
-    cap: Int
-): Int {
+fun knapsackDP(wgt: IntArray, _val: IntArray, cap: Int): Int {
     val n = wgt.size
     // 初始化 dp 表
     val dp = Array(n + 1) { IntArray(cap + 1) }
@@ -83,11 +79,7 @@ fun knapsackDP(
 }
 
 /* 0-1 背包：空间优化后的动态规划 */
-fun knapsackDPComp(
-    wgt: IntArray,
-    _val: IntArray,
-    cap: Int
-): Int {
+fun knapsackDPComp(wgt: IntArray, _val: IntArray, cap: Int): Int {
     val n = wgt.size
     // 初始化 dp 表
     val dp = IntArray(cap + 1)
@@ -97,8 +89,7 @@ fun knapsackDPComp(
         for (c in cap downTo 1) {
             if (wgt[i - 1] <= c) {
                 // 不选和选物品 i 这两种方案的较大值
-                dp[c] =
-                    max(dp[c], dp[c - wgt[i - 1]] + _val[i - 1])
+                dp[c] = max(dp[c], dp[c - wgt[i - 1]] + _val[i - 1])
             }
         }
     }
diff --git a/codes/kotlin/chapter_graph/graph_adjacency_list.kt b/codes/kotlin/chapter_graph/graph_adjacency_list.kt
index d58e4b178..47024610d 100644
--- a/codes/kotlin/chapter_graph/graph_adjacency_list.kt
+++ b/codes/kotlin/chapter_graph/graph_adjacency_list.kt
@@ -17,9 +17,9 @@ class GraphAdjList(edges: Array<Array<Vertex?>>) {
     init {
         // 添加所有顶点和边
         for (edge in edges) {
-            addVertex(edge[0]!!);
-            addVertex(edge[1]!!);
-            addEdge(edge[0]!!, edge[1]!!);
+            addVertex(edge[0]!!)
+            addVertex(edge[1]!!)
+            addEdge(edge[0]!!, edge[1]!!)
         }
     }
 
@@ -34,7 +34,7 @@ class GraphAdjList(edges: Array<Array<Vertex?>>) {
             throw IllegalArgumentException()
         // 添加边 vet1 - vet2
         adjList[vet1]?.add(vet2)
-        adjList[vet2]?.add(vet1);
+        adjList[vet2]?.add(vet1)
     }
 
     /* 删除边 */
@@ -42,8 +42,8 @@ class GraphAdjList(edges: Array<Array<Vertex?>>) {
         if (!adjList.containsKey(vet1) || !adjList.containsKey(vet2) || vet1 == vet2)
             throw IllegalArgumentException()
         // 删除边 vet1 - vet2
-        adjList[vet1]?.remove(vet2);
-        adjList[vet2]?.remove(vet1);
+        adjList[vet1]?.remove(vet2)
+        adjList[vet2]?.remove(vet1)
     }
 
     /* 添加顶点 */
@@ -59,7 +59,7 @@ class GraphAdjList(edges: Array<Array<Vertex?>>) {
         if (!adjList.containsKey(vet))
             throw IllegalArgumentException()
         // 在邻接表中删除顶点 vet 对应的链表
-        adjList.remove(vet);
+        adjList.remove(vet)
         // 遍历其他顶点的链表，删除所有包含 vet 的边
         for (list in adjList.values) {
             list.remove(vet)
diff --git a/codes/kotlin/chapter_graph/graph_adjacency_matrix.kt b/codes/kotlin/chapter_graph/graph_adjacency_matrix.kt
index c97e05dd0..7471f9bf0 100644
--- a/codes/kotlin/chapter_graph/graph_adjacency_matrix.kt
+++ b/codes/kotlin/chapter_graph/graph_adjacency_matrix.kt
@@ -69,8 +69,8 @@ class GraphAdjMat(vertices: IntArray, edges: Array<IntArray>) {
         if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
             throw IndexOutOfBoundsException()
         // 在无向图中，邻接矩阵关于主对角线对称，即满足 (i, j) == (j, i)
-        adjMat[i][j] = 1;
-        adjMat[j][i] = 1;
+        adjMat[i][j] = 1
+        adjMat[j][i] = 1
     }
 
     /* 删除边 */
@@ -79,15 +79,15 @@ class GraphAdjMat(vertices: IntArray, edges: Array<IntArray>) {
         // 索引越界与相等处理
         if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
             throw IndexOutOfBoundsException()
-        adjMat[i][j] = 0;
-        adjMat[j][i] = 0;
+        adjMat[i][j] = 0
+        adjMat[j][i] = 0
     }
 
     /* 打印邻接矩阵 */
     fun print() {
         print("顶点列表 = ")
-        println(vertices);
-        println("邻接矩阵 =");
+        println(vertices)
+        println("邻接矩阵 =")
         printMatrix(adjMat)
     }
 }
diff --git a/codes/kotlin/chapter_hashing/array_hash_map.kt b/codes/kotlin/chapter_hashing/array_hash_map.kt
index 1bcfe6ab5..f0bab31f1 100644
--- a/codes/kotlin/chapter_hashing/array_hash_map.kt
+++ b/codes/kotlin/chapter_hashing/array_hash_map.kt
@@ -68,7 +68,8 @@ class ArrayHashMap {
     fun valueSet(): MutableList<String> {
         val valueSet = mutableListOf<String>()
         for (pair in buckets) {
-            pair?.let { valueSet.add(it._val) }
+            if (pair != null)
+                valueSet.add(pair._val)
         }
         return valueSet
     }
@@ -78,7 +79,7 @@ class ArrayHashMap {
         for (kv in pairSet()) {
             val key = kv.key
             val _val = kv._val
-            println("${key} -> ${_val}")
+            println("$key -> $_val")
         }
     }
 }
diff --git a/codes/kotlin/chapter_hashing/built_in_hash.kt b/codes/kotlin/chapter_hashing/built_in_hash.kt
index 88bb3ff67..2ad958b04 100644
--- a/codes/kotlin/chapter_hashing/built_in_hash.kt
+++ b/codes/kotlin/chapter_hashing/built_in_hash.kt
@@ -28,7 +28,7 @@ fun main() {
 
     val arr = arrayOf<Any>(12836, "小哈")
     val hashTup = arr.contentHashCode()
-    println("数组 ${arr.contentToString()} 的哈希值为 ${hashTup}")
+    println("数组 ${arr.contentToString()} 的哈希值为 $hashTup")
 
     val obj = ListNode(0)
     val hashObj = obj.hashCode()
diff --git a/codes/kotlin/chapter_hashing/hash_map_chaining.kt b/codes/kotlin/chapter_hashing/hash_map_chaining.kt
index e59df4a6e..c8fdb8f2f 100644
--- a/codes/kotlin/chapter_hashing/hash_map_chaining.kt
+++ b/codes/kotlin/chapter_hashing/hash_map_chaining.kt
@@ -7,7 +7,7 @@
 package chapter_hashing
 
 /* 链式地址哈希表 */
-class HashMapChaining() {
+class HashMapChaining {
     var size: Int // 键值对数量
     var capacity: Int // 哈希表容量
     val loadThres: Double // 触发扩容的负载因子阈值
diff --git a/codes/kotlin/chapter_hashing/simple_hash.kt b/codes/kotlin/chapter_hashing/simple_hash.kt
index fdb51ef3c..a860eb84c 100644
--- a/codes/kotlin/chapter_hashing/simple_hash.kt
+++ b/codes/kotlin/chapter_hashing/simple_hash.kt
@@ -6,11 +6,10 @@
 
 package chapter_hashing
 
-const val MODULUS = 1000000007
-
 /* 加法哈希 */
 fun addHash(key: String): Int {
     var hash = 0L
+    val MODULUS = 1000000007
     for (c in key.toCharArray()) {
         hash = (hash + c.code) % MODULUS
     }
@@ -20,6 +19,7 @@ fun addHash(key: String): Int {
 /* 乘法哈希 */
 fun mulHash(key: String): Int {
     var hash = 0L
+    val MODULUS = 1000000007
     for (c in key.toCharArray()) {
         hash = (31 * hash + c.code) % MODULUS
     }
@@ -29,6 +29,7 @@ fun mulHash(key: String): Int {
 /* 异或哈希 */
 fun xorHash(key: String): Int {
     var hash = 0
+    val MODULUS = 1000000007
     for (c in key.toCharArray()) {
         hash = hash xor c.code
     }
@@ -38,6 +39,7 @@ fun xorHash(key: String): Int {
 /* 旋转哈希 */
 fun rotHash(key: String): Int {
     var hash = 0L
+    val MODULUS = 1000000007
     for (c in key.toCharArray()) {
         hash = ((hash shl 4) xor (hash shr 28) xor c.code.toLong()) % MODULUS
     }
diff --git a/codes/kotlin/chapter_heap/my_heap.kt b/codes/kotlin/chapter_heap/my_heap.kt
index 23b5b4f06..4381af22a 100644
--- a/codes/kotlin/chapter_heap/my_heap.kt
+++ b/codes/kotlin/chapter_heap/my_heap.kt
@@ -41,7 +41,9 @@ class MaxHeap(nums: MutableList<Int>?) {
 
     /* 交换元素 */
     private fun swap(i: Int, j: Int) {
-        maxHeap[i] = maxHeap[j].also { maxHeap[j] = maxHeap[i] }
+        val temp = maxHeap[i]
+        maxHeap[i] = maxHeap[j]
+        maxHeap[j] = temp
     }
 
     /* 获取堆大小 */
diff --git a/codes/kotlin/chapter_sorting/bubble_sort.kt b/codes/kotlin/chapter_sorting/bubble_sort.kt
index 12608d160..6f4f86b47 100644
--- a/codes/kotlin/chapter_sorting/bubble_sort.kt
+++ b/codes/kotlin/chapter_sorting/bubble_sort.kt
@@ -14,7 +14,9 @@ fun bubbleSort(nums: IntArray) {
         for (j in 0..<i) {
             if (nums[j] > nums[j + 1]) {
                 // 交换 nums[j] 与 nums[j + 1]
-                nums[j] = nums[j + 1].also { nums[j + 1] = nums[j] }
+                val temp = nums[j]
+                nums[j] = nums[j + 1]
+                nums[j + 1] = temp
             }
         }
     }
@@ -29,7 +31,9 @@ fun bubbleSortWithFlag(nums: IntArray) {
         for (j in 0..<i) {
             if (nums[j] > nums[j + 1]) {
                 // 交换 nums[j] 与 nums[j + 1]
-                nums[j] = nums[j + 1].also { nums[j] = nums[j + 1] }
+                val temp = nums[j]
+                nums[j] = nums[j + 1]
+                nums[j + 1] = temp
                 flag = true // 记录交换元素
             }
         }
diff --git a/codes/kotlin/chapter_sorting/heap_sort.kt b/codes/kotlin/chapter_sorting/heap_sort.kt
index a0f59448c..e7be26d24 100644
--- a/codes/kotlin/chapter_sorting/heap_sort.kt
+++ b/codes/kotlin/chapter_sorting/heap_sort.kt
@@ -22,7 +22,9 @@ fun siftDown(nums: IntArray, n: Int, li: Int) {
         if (ma == i) 
             break
         // 交换两节点
-        nums[i] = nums[ma].also { nums[ma] = nums[i] }
+        val temp = nums[i]
+        nums[i] = nums[ma]
+        nums[ma] = temp
         // 循环向下堆化
         i = ma
     }
@@ -37,7 +39,9 @@ fun heapSort(nums: IntArray) {
     // 从堆中提取最大元素，循环 n-1 轮
     for (i in nums.size - 1 downTo 1) {
         // 交换根节点与最右叶节点（交换首元素与尾元素）
-        nums[0] = nums[i].also { nums[i] = nums[0] }
+        val temp = nums[0]
+        nums[0] = nums[i]
+        nums[i] = temp
         // 以根节点为起点，从顶至底进行堆化
         siftDown(nums, i, 0)
     }
diff --git a/codes/kotlin/chapter_sorting/quick_sort.kt b/codes/kotlin/chapter_sorting/quick_sort.kt
index 09f8c91bb..77bfa9235 100644
--- a/codes/kotlin/chapter_sorting/quick_sort.kt
+++ b/codes/kotlin/chapter_sorting/quick_sort.kt
@@ -8,7 +8,9 @@ package chapter_sorting
 
 /* 元素交换 */
 fun swap(nums: IntArray, i: Int, j: Int) {
-    nums[i] = nums[j].also { nums[j] = nums[i] }
+    val temp = nums[i]
+    nums[i] = nums[j]
+    nums[j] = temp
 }
 
 /* 哨兵划分 */
diff --git a/codes/kotlin/chapter_sorting/selection_sort.kt b/codes/kotlin/chapter_sorting/selection_sort.kt
index 823d4ff70..653b7ab08 100644
--- a/codes/kotlin/chapter_sorting/selection_sort.kt
+++ b/codes/kotlin/chapter_sorting/selection_sort.kt
@@ -18,7 +18,9 @@ fun selectionSort(nums: IntArray) {
                 k = j // 记录最小元素的索引
         }
         // 将该最小元素与未排序区间的首个元素交换
-        nums[i] = nums[k].also { nums[k] = nums[i] }
+        val temp = nums[i]
+        nums[i] = nums[k]
+        nums[k] = temp
     }
 }
 
diff --git a/codes/kotlin/chapter_stack_and_queue/linkedlist_stack.kt b/codes/kotlin/chapter_stack_and_queue/linkedlist_stack.kt
index b63f3639a..434f0891d 100644
--- a/codes/kotlin/chapter_stack_and_queue/linkedlist_stack.kt
+++ b/codes/kotlin/chapter_stack_and_queue/linkedlist_stack.kt
@@ -34,7 +34,7 @@ class LinkedListStack(
     fun pop(): Int? {
         val num = peek()
         stackPeek = stackPeek?.next
-        stkSize--;
+        stkSize--
         return num
     }
 
diff --git a/codes/kotlin/chapter_tree/array_binary_tree.kt b/codes/kotlin/chapter_tree/array_binary_tree.kt
index 43e05de09..06c3b0c1f 100644
--- a/codes/kotlin/chapter_tree/array_binary_tree.kt
+++ b/codes/kotlin/chapter_tree/array_binary_tree.kt
@@ -10,7 +10,6 @@ import utils.TreeNode
 import utils.printTree
 
 /* 数组表示下的二叉树类 */
-/* 构造方法 */
 class ArrayBinaryTree(private val tree: MutableList<Int?>) {
     /* 列表容量 */
     fun size(): Int {
@@ -93,7 +92,7 @@ class ArrayBinaryTree(private val tree: MutableList<Int?>) {
 /* Driver Code */
 fun main() {
     // 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
+    // 这里借助了一个从列表直接生成二叉树的函数
     val arr = mutableListOf(1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15)
 
     val root = TreeNode.listToTree(arr)
diff --git a/codes/kotlin/chapter_tree/binary_tree_bfs.kt b/codes/kotlin/chapter_tree/binary_tree_bfs.kt
index 65e687721..9f5bf6c59 100644
--- a/codes/kotlin/chapter_tree/binary_tree_bfs.kt
+++ b/codes/kotlin/chapter_tree/binary_tree_bfs.kt
@@ -19,7 +19,7 @@ fun levelOrder(root: TreeNode?): MutableList<Int> {
     val list = mutableListOf<Int>()
     while (queue.isNotEmpty()) {
         val node = queue.poll()      // 队列出队
-        list.add(node?._val!!)      // 保存节点值
+        list.add(node?._val!!)       // 保存节点值
         if (node.left != null)
             queue.offer(node.left)   // 左子节点入队
         if (node.right != null)
@@ -31,7 +31,7 @@ fun levelOrder(root: TreeNode?): MutableList<Int> {
 /* Driver Code */
 fun main() {
     /* 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
+    // 这里借助了一个从列表直接生成二叉树的函数
     val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
     println("\n初始化二叉树\n")
     printTree(root)
diff --git a/codes/kotlin/chapter_tree/binary_tree_dfs.kt b/codes/kotlin/chapter_tree/binary_tree_dfs.kt
index cc101e26b..7a1ae8b9a 100644
--- a/codes/kotlin/chapter_tree/binary_tree_dfs.kt
+++ b/codes/kotlin/chapter_tree/binary_tree_dfs.kt
@@ -42,7 +42,7 @@ fun postOrder(root: TreeNode?) {
 /* Driver Code */
 fun main() {
     /* 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
+    // 这里借助了一个从列表直接生成二叉树的函数
     val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
     println("\n初始化二叉树\n")
     printTree(root)
diff --git a/codes/swift/chapter_dynamic_programming/climbing_stairs_backtrack.swift b/codes/swift/chapter_dynamic_programming/climbing_stairs_backtrack.swift
index d1e241bab..b5356ee5e 100644
--- a/codes/swift/chapter_dynamic_programming/climbing_stairs_backtrack.swift
+++ b/codes/swift/chapter_dynamic_programming/climbing_stairs_backtrack.swift
@@ -16,7 +16,9 @@ func backtrack(choices: [Int], state: Int, n: Int, res: inout [Int]) {
         if state + choice > n {
             continue
         }
+        // 尝试：做出选择，更新状态
         backtrack(choices: choices, state: state + choice, n: n, res: &res)
+        // 回退
     }
 }
 
diff --git a/docs/chapter_array_and_linkedlist/list.md b/docs/chapter_array_and_linkedlist/list.md
index 10cb41275..f764bd501 100755
--- a/docs/chapter_array_and_linkedlist/list.md
+++ b/docs/chapter_array_and_linkedlist/list.md
@@ -379,10 +379,10 @@
     nums.Add(4);
 
     /* 在中间插入元素 */
-    nums.Insert(3, 6);
+    nums.Insert(3, 6);  // 在索引 3 处插入数字 6
 
     /* 删除元素 */
-    nums.RemoveAt(3);
+    nums.RemoveAt(3);  // 删除索引 3 处的元素
     ```
 
 === "Go"
@@ -439,10 +439,10 @@
     nums.push(4);
 
     /* 在中间插入元素 */
-    nums.splice(3, 0, 6);
+    nums.splice(3, 0, 6); // 在索引 3 处插入数字 6
 
     /* 删除元素 */
-    nums.splice(3, 1);
+    nums.splice(3, 1);  // 删除索引 3 处的元素
     ```
 
 === "TS"
@@ -459,10 +459,10 @@
     nums.push(4);
 
     /* 在中间插入元素 */
-    nums.splice(3, 0, 6);
+    nums.splice(3, 0, 6); // 在索引 3 处插入数字 6
 
     /* 删除元素 */
-    nums.splice(3, 1);
+    nums.splice(3, 1);  // 删除索引 3 处的元素
     ```
 
 === "Dart"
diff --git a/docs/chapter_tree/array_representation_of_tree.md b/docs/chapter_tree/array_representation_of_tree.md
index 87e077f19..e49c128d3 100644
--- a/docs/chapter_tree/array_representation_of_tree.md
+++ b/docs/chapter_tree/array_representation_of_tree.md
@@ -117,7 +117,7 @@
     ```kotlin title=""
     /* 二叉树的数组表示 */
     // 使用 null 来表示空位
-    val tree = mutableListOf( 1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15 )
+    val tree = arrayOf( 1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15 )
     ```
 
 === "Ruby"