diff --git a/codes/kotlin/chapter_greedy/fractional_knapsack.kt b/codes/kotlin/chapter_greedy/fractional_knapsack.kt
index 0b375b66c..d95bfa58c 100644
--- a/codes/kotlin/chapter_greedy/fractional_knapsack.kt
+++ b/codes/kotlin/chapter_greedy/fractional_knapsack.kt
@@ -6,34 +6,28 @@
 
 package chapter_greedy
 
-import java.util.*
-
 /* 物品 */
 class Item(
     val w: Int, // 物品
-    val v: Int // 物品价值
+    val v: Int  // 物品价值
 )
 
 /* 分数背包：贪心 */
-fun fractionalKnapsack(
-    wgt: IntArray,
-    value: IntArray,
-    c: Int
-): Double {
+fun fractionalKnapsack(wgt: IntArray, _val: IntArray, c: Int): Double {
     // 创建物品列表，包含两个属性：重量、价值
     var cap = c
     val items = arrayOfNulls<Item>(wgt.size)
     for (i in wgt.indices) {
-        items[i] = Item(wgt[i], value[i])
+        items[i] = Item(wgt[i], _val[i])
     }
     // 按照单位价值 item.v / item.w 从高到低进行排序
-    Arrays.sort(items, Comparator.comparingDouble { item: Item -> -(item.v.toDouble() / item.w) })
+    items.sortBy { item: Item? -> -(item!!.v.toDouble() / item.w) }
     // 循环贪心选择
     var res = 0.0
     for (item in items) {
         if (item!!.w <= cap) {
             // 若剩余容量充足，则将当前物品整个装进背包
-            res += item.v.toDouble()
+            res += item.v
             cap -= item.w
         } else {
             // 若剩余容量不足，则将当前物品的一部分装进背包
diff --git a/codes/kotlin/chapter_greedy/max_capacity.kt b/codes/kotlin/chapter_greedy/max_capacity.kt
index ea9edfe27..9b4ffc7ef 100644
--- a/codes/kotlin/chapter_greedy/max_capacity.kt
+++ b/codes/kotlin/chapter_greedy/max_capacity.kt
@@ -19,8 +19,8 @@ fun maxCapacity(ht: IntArray): Int {
     // 循环贪心选择，直至两板相遇
     while (i < j) {
         // 更新最大容量
-        val cap = (min(ht[i].toDouble(), ht[j].toDouble()) * (j - i)).toInt()
-        res = max(res.toDouble(), cap.toDouble()).toInt()
+        val cap = min(ht[i], ht[j]) * (j - i)
+        res = max(res, cap)
         // 向内移动短板
         if (ht[i] < ht[j]) {
             i++
diff --git a/codes/kotlin/chapter_greedy/max_product_cutting.kt b/codes/kotlin/chapter_greedy/max_product_cutting.kt
index 9a24ce756..6945f8aac 100644
--- a/codes/kotlin/chapter_greedy/max_product_cutting.kt
+++ b/codes/kotlin/chapter_greedy/max_product_cutting.kt
@@ -19,14 +19,14 @@ fun maxProductCutting(n: Int): Int {
     val b = n % 3
     if (b == 1) {
         // 当余数为 1 时，将一对 1 * 3 转化为 2 * 2
-        return 3.0.pow((a - 1).toDouble()).toInt() * 2 * 2
+        return 3.0.pow((a - 1)).toInt() * 2 * 2
     }
     if (b == 2) {
         // 当余数为 2 时，不做处理
-        return 3.0.pow(a.toDouble()).toInt() * 2 * 2
+        return 3.0.pow(a).toInt() * 2 * 2
     }
     // 当余数为 0 时，不做处理
-    return 3.0.pow(a.toDouble()).toInt()
+    return 3.0.pow(a).toInt()
 }
 
 /* Driver Code */
diff --git a/codes/kotlin/chapter_hashing/array_hash_map.kt b/codes/kotlin/chapter_hashing/array_hash_map.kt
index fcf0879f9..8f9f60928 100644
--- a/codes/kotlin/chapter_hashing/array_hash_map.kt
+++ b/codes/kotlin/chapter_hashing/array_hash_map.kt
@@ -14,15 +14,9 @@ class Pair(
 
 /* 基于数组实现的哈希表 */
 class ArrayHashMap {
+    // 初始化数组，包含 100 个桶
     private val buckets = arrayOfNulls<Pair>(100)
 
-    init {
-        // 初始化数组，包含 100 个桶
-        for (i in 0..<100) {
-            buckets[i] = null
-        }
-    }
-
     /* 哈希函数 */
     fun hashFunc(key: Int): Int {
         val index = key % 100
@@ -52,25 +46,27 @@ class ArrayHashMap {
 
     /* 获取所有键值对 */
     fun pairSet(): MutableList<Pair> {
-        val pairSet = ArrayList<Pair>()
+        val pairSet = mutableListOf<Pair>()
         for (pair in buckets) {
-            if (pair != null) pairSet.add(pair)
+            if (pair != null)
+                pairSet.add(pair)
         }
         return pairSet
     }
 
     /* 获取所有键 */
     fun keySet(): MutableList<Int> {
-        val keySet = ArrayList<Int>()
+        val keySet = mutableListOf<Int>()
         for (pair in buckets) {
-            if (pair != null) keySet.add(pair.key)
+            if (pair != null)
+                keySet.add(pair.key)
         }
         return keySet
     }
 
     /* 获取所有值 */
     fun valueSet(): MutableList<String> {
-        val valueSet = ArrayList<String>()
+        val valueSet = mutableListOf<String>()
         for (pair in buckets) {
             pair?.let { valueSet.add(it.value) }
         }
@@ -82,7 +78,7 @@ class ArrayHashMap {
         for (kv in pairSet()) {
             val key = kv.key
             val value = kv.value
-            println("${key}->${value}")
+            println("${key} -> ${value}")
         }
     }
 }
@@ -104,7 +100,7 @@ fun main() {
 
     /* 查询操作 */
     // 向哈希表中输入键 key ，得到值 value
-    val name: String? = map.get(15937)
+    val name = map.get(15937)
     println("\n输入学号 15937 ，查询到姓名 $name")
 
     /* 删除操作 */
@@ -114,7 +110,7 @@ fun main() {
     map.print()
 
     /* 遍历哈希表 */
-    println("\n遍历键值对 Key->Value")
+    println("\n遍历键值对 Key -> Value")
     for (kv in map.pairSet()) {
         println("${kv.key} -> ${kv.value}")
     }
@@ -126,4 +122,4 @@ fun main() {
     for (value in map.valueSet()) {
         println(value)
     }
-}
+}
\ No newline at end of file
diff --git a/codes/kotlin/chapter_hashing/built_in_hash.kt b/codes/kotlin/chapter_hashing/built_in_hash.kt
index 948268800..88bb3ff67 100644
--- a/codes/kotlin/chapter_hashing/built_in_hash.kt
+++ b/codes/kotlin/chapter_hashing/built_in_hash.kt
@@ -11,15 +11,15 @@ import utils.ListNode
 /* Driver Code */
 fun main() {
     val num = 3
-    val hashNum = Integer.hashCode(num)
+    val hashNum = num.hashCode()
     println("整数 $num 的哈希值为 $hashNum")
 
     val bol = true
-    val hashBol = Boolean.hashCode()
+    val hashBol = bol.hashCode()
     println("布尔量 $bol 的哈希值为 $hashBol")
 
     val dec = 3.14159
-    val hashDec = java.lang.Double.hashCode(dec)
+    val hashDec = dec.hashCode()
     println("小数 $dec 的哈希值为 $hashDec")
 
     val str = "Hello 算法"
diff --git a/codes/kotlin/chapter_hashing/hash_map.kt b/codes/kotlin/chapter_hashing/hash_map.kt
index ffc468fee..1a7ef1208 100644
--- a/codes/kotlin/chapter_hashing/hash_map.kt
+++ b/codes/kotlin/chapter_hashing/hash_map.kt
@@ -11,7 +11,7 @@ import utils.printHashMap
 /* Driver Code */
 fun main() {
     /* 初始化哈希表 */
-    val map: MutableMap<Int, String> = HashMap()
+    val map = HashMap<Int, String>()
 
     /* 添加操作 */
     // 在哈希表中添加键值对 (key, value)
diff --git a/codes/kotlin/chapter_hashing/hash_map_chaining.kt b/codes/kotlin/chapter_hashing/hash_map_chaining.kt
index 205db6df5..d8558631b 100644
--- a/codes/kotlin/chapter_hashing/hash_map_chaining.kt
+++ b/codes/kotlin/chapter_hashing/hash_map_chaining.kt
@@ -20,7 +20,7 @@ class HashMapChaining() {
         capacity = 4
         loadThres = 2.0 / 3.0
         extendRatio = 2
-        buckets = ArrayList(capacity)
+        buckets = mutableListOf()
         for (i in 0..<capacity) {
             buckets.add(mutableListOf())
         }
diff --git a/codes/kotlin/chapter_hashing/hash_map_open_addressing.kt b/codes/kotlin/chapter_hashing/hash_map_open_addressing.kt
index 58a3c2d76..d95a436a2 100644
--- a/codes/kotlin/chapter_hashing/hash_map_open_addressing.kt
+++ b/codes/kotlin/chapter_hashing/hash_map_open_addressing.kt
@@ -8,16 +8,21 @@ package chapter_hashing
 
 /* 开放寻址哈希表 */
 class HashMapOpenAddressing {
-    private var size: Int = 0 // 键值对数量
-    private var capacity = 4 // 哈希表容量
-    private val loadThres: Double = 2.0 / 3.0 // 触发扩容的负载因子阈值
-    private val extendRatio = 2 // 扩容倍数
-    private var buckets: Array<Pair?> // 桶数组
-    private val TOMBSTONE = Pair(-1, "-1") // 删除标记
+    private var size: Int               // 键值对数量
+    private var capacity: Int           // 哈希表容量
+    private val loadThres: Double       // 触发扩容的负载因子阈值
+    private val extendRatio: Int        // 扩容倍数
+    private var buckets: Array<Pair?>   // 桶数组
+    private val TOMBSTONE: Pair         // 删除标记
 
     /* 构造方法 */
     init {
+        size = 0
+        capacity = 4
+        loadThres = 2.0 / 3.0
+        extendRatio = 2
         buckets = arrayOfNulls(capacity)
+        TOMBSTONE = Pair(-1, "-1")
     }
 
     /* 哈希函数 */
diff --git a/codes/kotlin/chapter_hashing/simple_hash.kt b/codes/kotlin/chapter_hashing/simple_hash.kt
index a4353361b..fdb51ef3c 100644
--- a/codes/kotlin/chapter_hashing/simple_hash.kt
+++ b/codes/kotlin/chapter_hashing/simple_hash.kt
@@ -6,7 +6,7 @@
 
 package chapter_hashing
 
-const val MODULUS = 10_0000_0007
+const val MODULUS = 1000000007
 
 /* 加法哈希 */
 fun addHash(key: String): Int {
@@ -48,7 +48,7 @@ fun rotHash(key: String): Int {
 fun main() {
     val key = "Hello 算法"
 
-    var hash: Int = addHash(key)
+    var hash = addHash(key)
     println("加法哈希值为 $hash")
 
     hash = mulHash(key)
diff --git a/codes/kotlin/chapter_heap/heap.kt b/codes/kotlin/chapter_heap/heap.kt
index 08eef31be..1e0365c1f 100644
--- a/codes/kotlin/chapter_heap/heap.kt
+++ b/codes/kotlin/chapter_heap/heap.kt
@@ -25,7 +25,7 @@ fun testPop(heap: Queue<Int>) {
 fun main() {
     /* 初始化堆 */
     // 初始化小顶堆
-    val minHeap: PriorityQueue<Int>
+    var minHeap = PriorityQueue<Int>()
 
     // 初始化大顶堆（使用 lambda 表达式修改 Comparator 即可）
     val maxHeap = PriorityQueue { a: Int, b: Int -> b - a }
diff --git a/codes/kotlin/chapter_heap/my_heap.kt b/codes/kotlin/chapter_heap/my_heap.kt
index 9d0ad0c73..1a63ed8d1 100644
--- a/codes/kotlin/chapter_heap/my_heap.kt
+++ b/codes/kotlin/chapter_heap/my_heap.kt
@@ -10,13 +10,14 @@ import utils.printHeap
 import java.util.*
 
 /* 大顶堆 */
-class MaxHeap(nums: List<Int>?) {
+class MaxHeap(nums: MutableList<Int>?) {
     // 使用列表而非数组，这样无须考虑扩容问题
-    // 将列表元素原封不动添加进堆
-    private val maxHeap = ArrayList(nums!!)
+    private val maxHeap = mutableListOf<Int>()
 
-    /* 构造函数，根据输入列表建堆 */
+    /* 构造方法，根据输入列表建堆 */
     init {
+        // 将列表元素原封不动添加进堆
+        maxHeap.addAll(nums!!)
         // 堆化除叶节点以外的其他所有节点
         for (i in parent(size() - 1) downTo 0) {
             siftDown(i)
diff --git a/codes/kotlin/chapter_searching/hashing_search.kt b/codes/kotlin/chapter_searching/hashing_search.kt
index cbc0d9fbb..872c98985 100644
--- a/codes/kotlin/chapter_searching/hashing_search.kt
+++ b/codes/kotlin/chapter_searching/hashing_search.kt
@@ -7,7 +7,6 @@
 package chapter_searching
 
 import utils.ListNode
-import java.util.HashMap
 
 /* 哈希查找（数组） */
 fun hashingSearchArray(map: Map<Int?, Int>, target: Int): Int {