lru 缓存

Author: baxiang

Go/leetcode/146lru-cache/main.go

@@ -0,0 +1,92 @@
+package main
+
+import "fmt"
+
+type Node struct {
+	key int
+	value int
+	pre *Node
+	next *Node
+}
+
+type LRUCache struct {
+     m map[int] *Node
+     head *Node
+     tail *Node
+	 capacity int
+}
+
+
+func Constructor(capacity int) LRUCache {
+    cache := LRUCache{
+		  m:        make(map[int]*Node),
+		  head:     &Node{},
+		  tail:     &Node{},
+		  capacity: capacity,
+	  }
+	  cache.head.next = cache.tail
+	  cache.tail.pre = cache.head
+	  return cache
+}
+// 头部添加元素
+func (this *LRUCache)AddHead(n *Node){
+	 tmp := this.head.next
+	 this.head.next = n
+	 n.next = tmp
+	 n.pre = this.head
+	 tmp.pre = n
+}
+func (this *LRUCache)RemoveNode(n *Node){
+	pre := n.pre
+	next := n.next
+	pre.next = next
+	next.pre = pre
+	n.pre = nil
+	n.next = nil
+}
+
+
+func (this *LRUCache) Get(key int) int {
+	node ,ok:= this.m[key]
+	if ok {
+		this.RemoveNode(node)
+		this.AddHead(node)
+		return node.value
+	}
+	return -1
+}
+
+
+func (this *LRUCache) Put(key int, value int)  {
+	node ,ok:= this.m[key]
+	if ok {// 存在
+		if node.value!= value {
+			node.value = value
+		}
+		this.RemoveNode(node)
+		this.AddHead(node)
+	}else {
+		n := &Node{
+			key:key,
+			value: value,
+		}
+		if this.capacity==len(this.m) {// 删除
+			delete(this.m,this.tail.pre.key)
+			this.RemoveNode(this.tail.pre)
+		}
+		this.AddHead(n)
+		this.m[key] = n
+	}
+}
+func main() {
+	cache := Constructor(2)
+	cache.Put(1,1)
+	cache.Put(2,2)
+	fmt.Println(cache.Get(1))//1
+	cache.Put(3,3)
+	fmt.Println(cache.Get(2))//-1
+	cache.Put(4,4)
+	fmt.Println(cache.Get(1))//-1
+	fmt.Println(cache.Get(3))//3
+	fmt.Println(cache.Get(4))//4
+}