添加跳表代码

skiptable.go

@@ -0,0 +1,168 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+// 定义跳表节点结构
+type SkipListNode struct {
+	key   string // 键
+	value interface{} // 值
+	forward []*SkipListNode // 指向下一节点的指针数组
+}
+
+// 定义跳表结构
+type SkipList struct {
+	head *SkipListNode // 头节点
+	level int          // 当前跳表的最大层数
+	maxLevel int       // 跳表允许的最大层数
+}
+
+// 创建一个新的跳表
+func NewSkipList(maxLevel int) *SkipList {
+	return &SkipList{
+		head:     &SkipListNode{forward: make([]*SkipListNode, maxLevel)},
+		level:    0,
+		maxLevel: maxLevel,
+	}
+}
+
+// 随机生成层数
+func randomLevel() int {
+	rand.Seed(time.Now().UnixNano())
+	level := 1
+	for rand.Float64() < 0.5 && level < 16 { // 最大层数限制为16
+		level++
+	}
+	return level
+}
+
+// 插入键值对
+func (sl *SkipList) Insert(key string, value interface{}) {
+	update := make([]*SkipListNode, sl.maxLevel)
+	current := sl.head
+
+	// 找到每一层需要更新的节点
+	for i := sl.level - 1; i >= 0; i-- {
+		for current.forward[i] != nil && current.forward[i].key < key {
+			current = current.forward[i]
+		}
+		update[i] = current
+	}
+
+	// 如果键已经存在，则更新其值
+	if current.forward[0] != nil && current.forward[0].key == key {
+		current.forward[0].value = value
+		return
+	}
+
+	// 确定新节点的层数
+	newLevel := randomLevel()
+	if newLevel > sl.level {
+		for i := sl.level; i < newLevel; i++ {
+			update[i] = sl.head
+		}
+		sl.level = newLevel
+	}
+
+	// 创建新节点并更新指针
+	newNode := &SkipListNode{key: key, value: value, forward: make([]*SkipListNode, newLevel)}
+	for i := 0; i < newLevel; i++ {
+		newNode.forward[i] = update[i].forward[i]
+		update[i].forward[i] = newNode
+	}
+}
+
+// 查找键对应的值
+func (sl *SkipList) Search(key string) (interface{}, bool) {
+	current := sl.head
+
+	// 找到目标节点
+	for i := sl.level - 1; i >= 0; i-- {
+		for current.forward[i] != nil && current.forward[i].key < key {
+			current = current.forward[i]
+		}
+	}
+
+	current = current.forward[0]
+	if current != nil && current.key == key {
+		return current.value, true
+	}
+	return nil, false
+}
+
+// 删除键值对
+func (sl *SkipList) Delete(key string) bool {
+	update := make([]*SkipListNode, sl.maxLevel)
+	current := sl.head
+
+	// 找到每一层需要更新的节点
+	for i := sl.level - 1; i >= 0; i-- {
+		for current.forward[i] != nil && current.forward[i].key < key {
+			current = current.forward[i]
+		}
+		update[i] = current
+	}
+
+	current = current.forward[0]
+	if current != nil && current.key == key {
+		for i := 0; i < sl.level; i++ {
+			if update[i].forward[i] != current {
+				break
+			}
+			update[i].forward[i] = current.forward[i]
+		}
+
+		// 更新当前跳表的层数
+		for sl.level > 1 && sl.head.forward[sl.level-1] == nil {
+			sl.level--
+		}
+		return true
+	}
+	return false
+}
+
+// 打印跳表（仅用于调试）
+func (sl *SkipList) Print() {
+	for i := sl.level - 1; i >= 0; i-- {
+		fmt.Printf("Level %d: ", i)
+		current := sl.head.forward[i]
+		for current != nil {
+			fmt.Printf("(%s:%v) -> ", current.key, current.value)
+			current = current.forward[i]
+		}
+		fmt.Println("nil")
+	}
+}
+
+func main() {
+	skipList := NewSkipList(16)
+
+	// 插入一些键值对
+	skipList.Insert("apple", 3)
+	skipList.Insert("banana", 5)
+	skipList.Insert("cherry", 7)
+	skipList.Insert("date", 9)
+
+	// 打印跳表
+	skipList.Print()
+
+	// 查找键对应的值
+	if val, found := skipList.Search("banana"); found {
+		fmt.Printf("Search 'banana': %v\n", val)
+	} else {
+		fmt.Println("Search 'banana': not found")
+	}
+
+	// 删除键值对
+	if skipList.Delete("banana") {
+		fmt.Println("Deleted 'banana'")
+	} else {
+		fmt.Println("Delete 'banana': not found")
+	}
+
+	// 再次打印跳表
+	skipList.Print()
+}