146. LRU 缓存

[chunbin1]

思路： 利用Map有顺序的原理

1. get的时候从map中删除，再塞回去。
2. put的时候先把有的delete掉，然后如果超过缓存最大值，就删除第一个

   
   /**
   * @param {number} capacity
   */
   var LRUCache = function(capacity) {
   this.capacity = capacity;
   this.map = new Map();
   };

/**

• @param {number} key
• @return {number} */ LRUCache.prototype.get = function(key) { if(this.map.has(key)){ let temp=this.map.get(key) this.map.delete(key); this.map.set(key, temp); return temp }else{ return -1 } };

/**

• @param {number} key
• @param {number} value

• @return {void} */ LRUCache.prototype.put = function(key, value) { if(this.map.has(key)){ this.map.delete(key); } this.map.set(key,value); if(this.map.size > this.capacity){

  this.map.delete(this.map.keys().next().value);

  } };

/**

• Your LRUCache object will be instantiated and called as such:
• var obj = new LRUCache(capacity)
• var param_1 = obj.get(key)
• obj.put(key,value) */

[chunbin1]

使用数组来记录key

class Cache {
    constructor(size = 1) {
        this.size = size
        this.keyArr = []
        this.keyValueMap = new Map()
    }

    get(key) {
        debugger
        const val = this.keyValueMap.get(key)
        if (val) {
            const idx = this.keyArr.indexOf(key)
            this.keyArr.splice(idx, 1)
            this.keyArr.unshift(key)
            return val
        }
        return -1
    }

    put(key, val) {
        if (this.keyValueMap.size >= this.size) {
            // 缓存淘汰
            const deleteKey = this.keyArr.pop()
            this.keyValueMap.delete(deleteKey)

        }
        // 缓存进入
        this.keyValueMap.set(key, val)
        this.keyArr.push(key)
    }
}