其实按道理,应该自己写一个,LRU原则就是最近最少使用,每次添加的时候,将最少使用的删除掉。使用一次就放到栈顶,移除的时候就是移除栈底。或者使用一次放到队头,移除的时候就是移除队尾

import java.util.*;


public class Solution {
    Map<Integer, Integer> map;
    int capacity;
    public Solution(int capacity) {
         // write code here
        this.capacity = capacity;
        map = new LinkedHashMap<Integer,Integer>(capacity, 0.75f,true){
            @Override
            protected boolean removeEldestEntry(Map.Entry<Integer,Integer> eldest){
                return super.size() > capacity;
            }
        };
    }

    public int get(int key) {
         // write code here
        if(!map.containsKey(key)){
            return -1;
        }
        return map.get(key);
    }

    public void set(int key, int value) {
         // write code here
        map.put(key, value);
    }
}


/**
 * Your Solution object will be instantiated and called as such:
 * Solution solution = new Solution(capacity);
 * int output = solution.get(key);
 * solution.set(key,value);
 */