标签：number else dia The structure remove operation == --
146. LRU Cache
Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and put.
get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.put(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.
The cache is initialized with a positive capacity.
Follow up:
Could you do both operations in O(1) time complexity?
Example:
LRUCache cache = new LRUCache( 2 /* capacity */ ); cache.put(1, 1); cache.put(2, 2); cache.get(1); // returns 1 cache.put(3, 3); // evicts key 2 cache.get(2); // returns -1 (not found) cache.put(4, 4); // evicts key 1 cache.get(1); // returns -1 (not found) cache.get(3); // returns 3 cache.get(4); // returns 4
题意：构建一个类和一个数据结构LRUCache，有get和put两个方法，get方法用于获取LRUCache中的值，不存在返回-1；put方法用于向LRUCache存入数值，当达到它的容量时，替换最近最少使用的
代码如下：
/** * @param {number} capacity */ var LRUCache = function(capacity) { this.capacity=capacity; this.count=0; this.head=null; this.tail=null; this.hashTable={}; }; /** * @param {number} key * @return {number} */ LRUCache.prototype.get = function(key) { if(this.hashTable[key]){ const {value}=this.hashTable[key]; const {prev , next}=this.hashTable[key]; if(prev) prev.next=next; if(next) next.prev=prev || next.prev; if(this.tail===this.hashTable[key]){ this.tail=prev || this.hashTable[key]; } this.hashTable[key].prev=null; if(this.head!==this.hashTable[key]){ this.hashTable[key].next=this.head; this.head.prev=this.hashTable[key]; } this.head=this.hashTable[key]; return value; } return -1; }; /** * @param {number} key * @param {number} value * @return {void} */ LRUCache.prototype.put = function(key, value) { if(this.hashTable[key]){ this.hashTable[key].value=value; this.get(key); }else{ this.hashTable[key]={key,value,prev:null,next:null}; if(this.head){ this.head.prev=this.hashTable[key]; this.hashTable[key].next=this.head; } this.head=this.hashTable[key]; if(!this.tail){ this.tail=this.hashTable[key]; } this.count++; } if(this.count>this.capacity){ let removeKey=this.tail.key; if(this.tail.prev){ this.tail.prev.next=null; this.tail=this.tail.prev; this.hashTable[key].prev=null; } delete this.hashTable[removeKey]; this.count--; } }; /** * Your LRUCache object will be instantiated and called as such: * var obj = Object.create(LRUCache).createNew(capacity) * var param_1 = obj.get(key) * obj.put(key,value) */
标签：number else dia The structure remove operation == --
原文地址：https://www.cnblogs.com/xingguozhiming/p/11061779.html
