leetcode LRU Cache Golang

package mainimport("fmt")type Node struct {Key stringVal stringPre *NodeNext *Node}type DLinkedList struct {Head *NodeTail *Node}func (self *DLinkedList) IsEmpty() bool {if self.Head == nil && self.Tail == nil {return true} else {return false}}func (self *DLinkedList) RemoveLast() {if self.Tail != nil {self.Remove(self.Tail)}}func (self *DLinkedList) Remove(n *Node){if self.Tail == self.Head {self.Head = nilself.Tail = nilreturn}if n == self.Head {n.Next.Pre = nilself.Head = n.Nextreturn}if n == self.Tail {n.Pre.Next = nilself.Tail = n.Prereturn}n.Pre.Next = n.Nextn.Next.Pre = n.Pre}func (self *DLinkedList) AddFirst(n *Node) {if self.Head == nil {self.Head = nself.Tail = nn.Pre = niln.Next = nilreturn}n.Next = self.Headself.Head.Pre = n    self.Head = n    n.Pre = nil}type LRUCache struct {Cap intSize intHashMap map[string]*NodeCache *DLinkedList}func (self *LRUCache) Get(k string) string {if node,ok := self.HashMap[k]; ok {self.Cache.Remove(node)self.Cache.AddFirst(node)return node.Val} else {return ""}}func (self *LRUCache) Set(k,val string ) {if node,ok := self.HashMap[k];ok {self.Cache.Remove(node)node.Val = valself.Cache.AddFirst(node)} else {n := &Node{Key:k,Val:val}self.HashMap[k] = nself.Cache.AddFirst(n)self.Size = self.Size + 1if self.Size > self.Cap {self.Size = self.Size - 1delete(self.HashMap,self.Cache.Tail.Key)self.Cache.RemoveLast()}}}func main() {cache := new(LRUCache)cache.Cap = 3cache.HashMap = make(map[string]*Node,0)cache.Cache = new(DLinkedList)cache.Set("allen","value")cache.Set("a","value")cache.Set("b","value")cache.Set("c","value")test := cache.Get("allen")fmt.Println(test)fmt.Println(cache.HashMap)fmt.Println(cache.Cache)fmt.Println(cache.Size)}