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@@ -0,0 +1,106 @@
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+type biNode struct {
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+ key int
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+ val int
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+ cnt int
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+ prev *biNode
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+ next *biNode
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+}
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+
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+type biList struct {
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+ head *biNode
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+ tail *biNode
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+}
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+
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+func newBiList() *biList {
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+ head, tail := &biNode{}, &biNode{}
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+ head.next = tail
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+ tail.prev = head
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+ li := &biList{head, tail}
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+ return li
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+}
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+
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+func (li *biList) remove(node *biNode) {
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+ node.prev.next = node.next
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+ node.next.prev = node.prev
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+}
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+
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+type LFUCache struct {
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+ capacity int
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+ size int
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+ min int
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+ cache map[int]*biNode
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+ freq map[int]*biList
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+}
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+
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+func Constructor(capacity int) LFUCache {
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+ var lfu LFUCache
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+ lfu.capacity = capacity
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+ lfu.cache = make(map[int]*biNode)
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+ lfu.freq = make(map[int]*biList)
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+ return lfu
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+}
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+
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+func (this *LFUCache) Get(key int) int {
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+ if node, ok := this.cache[key]; ok {
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+ this.touch(node)
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+ return node.val
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+ }
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+ return -1
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+}
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+
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+func (this *LFUCache) Put(key int, value int) {
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+ if this.capacity == 0 {
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+ return
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+ } // Can not put new node.
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+ if node, ok := this.cache[key]; ok {
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+ this.touch(node)
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+ node.val = value
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+ return
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+ } // If the key already exists, touch it and update the value.
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+ if this.size == this.capacity {
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+ li := this.freq[this.min]
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+ delete(this.cache, li.tail.prev.key)
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+ li.remove(li.tail.prev)
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+ if li.head.next == li.tail {
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+ delete(this.freq, this.min)
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+ }
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+ this.size--
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+ } // If the cache is full, remove the last element in the least freq list.
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+ newNode := &biNode{key, value, 1, nil, nil}
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+ this.insert(newNode)
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+ this.cache[key] = newNode
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+ this.min = 1
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+ this.size++ // Then, insert new node.
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+}
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+
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+func (this *LFUCache) insert(node *biNode) {
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+ li := this.freq[node.cnt]
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+ if li == nil {
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+ li = newBiList()
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+ this.freq[node.cnt] = li
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+ }
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+ node.next = li.head.next
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+ node.prev = li.head
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+ li.head.next = node
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+ node.next.prev = node
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+}
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+
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+func (this *LFUCache) touch(node *biNode) {
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+ li := this.freq[node.cnt]
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+ li.remove(node)
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+ if li.head.next == li.tail {
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+ delete(this.freq, node.cnt)
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+ if node.cnt == this.min {
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+ this.min++
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+ }
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+ }
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+ node.cnt++
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+ this.insert(node)
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+}
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+
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+/**
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+ * Your LFUCache object will be instantiated and called as such:
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+ * obj := Constructor(capacity);
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+ * param_1 := obj.Get(key);
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+ * obj.Put(key,value);
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+ */
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