feat(hashing/hash_map_collision_with_linkedlist): Add go code

codes/go/chapter_hashing/hash_map_collision_with_linkedlist.go

@@ -0,0 +1,157 @@
+// File: hash_map_collision_with_linkedlist.go
+// Created Time: 2023-05-18
+// Author: msk397 (icbigdata@gmail.com)
+
+package chapter_hashing
+
+import (
+	"fmt"
+)
+
+/* 基于数组简易实现的哈希表，hash key冲突时，使用链表存储冲突key */
+type arrayHashMapWithLinkedList struct {
+	buckets []*entryList
+}
+
+/* 键值对 int->String */
+type entryList struct {
+	key int
+	val string
+	// hash key 冲突时，使用链表连接起来
+	next *entryList
+}
+
+/* 使用别名，简化变量 */
+type myMap = arrayHashMapWithLinkedList
+
+var NotFoundKey = "not_found"
+
+/* 初始化哈希表 */
+func newArrayHashMapWithLinkedList(bucketSize int) *myMap {
+	// 初始化数组，包含 100 个桶
+	buckets := make([]*entryList, bucketSize)
+	return &arrayHashMapWithLinkedList{buckets: buckets}
+}
+
+/* 哈希函数 */
+func (a *myMap) hashFunc(key int) int {
+	size := len(a.buckets)
+	index := key % size
+	return index
+}
+
+func (a *myMap) getEntry(key int) *entryList {
+	index := a.hashFunc(key)
+	pair := a.buckets[index]
+	if pair == nil {
+		return nil
+	}
+	if pair.key == key {
+		return pair
+	}
+	// 进一步通过链表查询
+	for pair.next != nil {
+		pair = pair.next
+		if pair.key == key {
+			return pair
+		}
+	}
+	return nil
+}
+
+/* 查询操作 */
+func (a *myMap) get(key int) string {
+	entry := a.getEntry(key)
+	if entry == nil {
+		return NotFoundKey
+	}
+	return entry.val
+}
+
+/* 添加操作 */
+func (a *myMap) put(key int, val string) {
+	entry := a.getEntry(key)
+	if entry == nil {
+		pair := &entryList{key: key, val: val}
+		index := a.hashFunc(key)
+		head := a.buckets[index]
+		if head != nil {
+			// hash key 冲突, 头插法，将新节点插入链表的头部
+			pair.next = head
+		}
+		a.buckets[index] = pair
+	} else {
+		entry.val = val
+	}
+}
+
+/* 删除操作 */
+func (a *myMap) remove(key int) {
+	index := a.hashFunc(key)
+	// 置为 nil ，代表删除
+	pair := a.buckets[index]
+	if pair == nil {
+		return
+	}
+	if pair.key == key {
+		next := pair.next
+		a.buckets[index] = next
+	} else {
+		pre := pair
+		for pair.next != nil {
+			pair = pair.next
+			if pair.key == key {
+				pre.next = pair.next
+				return
+			}
+			pre = pair
+		}
+	}
+}
+
+/* 获取所有键对 */
+func (a *myMap) entrySet() []*entry {
+	var pairs []*entry
+	for _, pair := range a.buckets {
+		for pair != nil {
+			e := &entry{pair.key, pair.val}
+			pairs = append(pairs, e)
+			pair = pair.next
+		}
+	}
+	return pairs
+}
+
+/* 获取所有键 */
+func (a *myMap) keySet() []int {
+	var keys []int
+	for _, pair := range a.buckets {
+		for pair != nil {
+			keys = append(keys, pair.key)
+			pair = pair.next
+		}
+	}
+	return keys
+}
+
+/* 获取所有值 */
+func (a *myMap) valueSet() []string {
+	var values []string
+	for _, pair := range a.buckets {
+		for pair != nil {
+			values = append(values, pair.val)
+			pair = pair.next
+		}
+	}
+	return values
+}
+
+/* 打印哈希表 */
+func (a *myMap) print() {
+	for _, pair := range a.buckets {
+		for pair != nil {
+			fmt.Println(pair.key, "->", pair.val)
+			pair = pair.next
+		}
+	}
+}

codes/go/chapter_hashing/hash_map_collision_with_linkedlist_test.go

@@ -0,0 +1,85 @@
+// File: hash_map_collision_with_linkedlist_test.go
+// Created Time: 2023-05-18
+// Author: msk397 (icbigdata@gmail.com)
+
+package chapter_hashing
+
+import (
+	"fmt"
+	"testing"
+)
+
+func Test_newArrayHashMapWithLinkedList(t *testing.T) {
+	/* 初始化哈希表 */
+	mapp := newArrayHashMapWithLinkedList(100)
+
+	/* 添加操作 */
+	// 在哈希表中添加键值对 (key, value)
+	mapp.put(12836, "小哈")
+	mapp.put(15937, "小啰")
+	mapp.put(16750, "小算")
+	mapp.put(13276, "小法")
+	mapp.put(10583, "小鸭")
+
+	// 构hash key冲突
+	mapp.put(20583, "小鸭2")
+	mapp.put(30583, "小鸭3")
+	mapp.put(40583, "小鸭4")
+
+	fmt.Println("\n添加完成后，哈希表为\nKey -> Value")
+	mapp.print()
+
+	/* 更新key的val */
+	mapp.put(10583, "小鸭1")
+	fmt.Println("\n更新学号 10583 ，姓名为 小鸭1")
+	mapp.print()
+	/* 查询操作 */
+	// 向哈希表输入键 key ，得到值 value
+	name := mapp.get(15937)
+	fmt.Println("\n输入学号 15937 ，查询到姓名 " + name)
+
+	/* 查询操作 */
+	// 向哈希表输入键 key ，得到值 value
+	name = mapp.get(20583)
+	fmt.Println("\n输入学号 20583 ，查询到姓名 " + name)
+
+	/* 删除操作 */
+	// 在哈希表中删除键值对 (key, value)
+	mapp.remove(12836)
+	fmt.Println("\n删除 12836 后，哈希表为\nKey -> Value")
+	mapp.print()
+
+	/* 删除操作 */
+	// 在哈希表中删除键值对 (key, value)
+	mapp.remove(10583)
+	fmt.Println("\n删除 10583 后，哈希表为\nKey -> Value")
+	mapp.print()
+
+	/* 删除操作 */
+	// 在哈希表中删除键值对 (key, value)
+	mapp.remove(30583)
+	fmt.Println("\n删除 30583 后，哈希表为\nKey -> Value")
+	mapp.print()
+
+	/* 删除操作 */
+	// 在哈希表中删除键值对 (key, value)
+	mapp.remove(40583)
+	fmt.Println("\n删除 40583 后，哈希表为\nKey -> Value")
+	mapp.print()
+
+	/* 遍历哈希表 */
+	fmt.Println("\n遍历键值对 Key->Value")
+	for _, kv := range mapp.entrySet() {
+		fmt.Println(kv.key, " -> ", kv.val)
+	}
+
+	fmt.Println("\n单独遍历键 Key")
+	for _, key := range mapp.keySet() {
+		fmt.Println(key)
+	}
+
+	fmt.Println("\n单独遍历值 Value")
+	for _, val := range mapp.valueSet() {
+		fmt.Println(val)
+	}
+}