LeetCode146-LRU缓存机制
作者:互联网
题目:
运用你所掌握的数据结构,设计和实现一个 LRU (最近最少使用) 缓存机制 。
实现 LRUCache 类:
LRUCache(int capacity) 以正整数作为容量 capacity 初始化 LRU 缓存
int get(int key) 如果关键字 key 存在于缓存中,则返回关键字的值,否则返回 -1 。
void put(int key, int value): 如果关键字已经存在,则变更其数据值;
如果关键字不存在,则插入该组「关键字-值」。
当缓存容量达到上限时,它应该在写入新数据之前删除最久未使用的数据值,从而为新的数据值留出空间。
链接:https://leetcode-cn.com/problems/lru-cache
解法1:
class LRUCache {
private int cacheSize;
private LinkedHashMap<Integer,Integer> map;
public LRUCache(int capacity) {
this.cacheSize = capacity;
map = new LinkedHashMap<>(cacheSize,0.75F,true){
@Override
protected boolean removeEldestEntry(Map.Entry<Integer,Integer> eldest){
return size() > cacheSize;
}
};
}
public int get(int key) {
return map.getOrDefault(key,-1);
}
public void put(int key, int value) {
map.put(key,value);
}
}
/**
* Your LRUCache object will be instantiated and called as such:
* LRUCache obj = new LRUCache(capacity);
* int param_1 = obj.get(key);
* obj.put(key,value);
*/
解法2
class LRUCache {
private HashMap<Integer, Node> map;
private int cacheSize;
private LinkedNodeList cache;
public LRUCache(int capacity) {
this.cacheSize = capacity;
map = new HashMap<>();
cache = new LinkedNodeList();
}
public int get(int key) {
if (!map.containsKey(key))
return -1;
Node res = map.get(key);
cache.remove(res);
cache.addFirst(res);
return res.value;
}
public void put(int key, int value) {
Node newnode = new Node(key, value);
if (map.containsKey(key)) {
cache.remove(map.get(key));
cache.addFirst(newnode);
map.put(key, newnode);
} else {
if (cacheSize == map.size()) {
Node lastnode = cache.removeLast();
map.remove(lastnode.key);
}
cache.addFirst(newnode);
map.put(key, newnode);
}
}
}
class Node {
int key;
int value;
Node prev;
Node next;
public Node() {
}
public Node(int k, int v) {
this.key = k;
this.value = v;
}
}
class LinkedNodeList {
Node head;
Node tail;
public LinkedNodeList() {
head = new Node(0, 0);
tail = new Node(0, 0);
head.next = tail;
tail.prev = head;
}
public void addFirst(Node n) {
head.next.prev = n;
n.next = head.next;
n.prev = head;
head.next = n;
}
public void remove(Node n) {
n.prev.next = n.next;
n.next.prev = n.prev;
}
public Node removeLast() {
Node res = tail.prev;
remove(res);
return res;
}
}
/**
* Your LRUCache object will be instantiated and called as such:
* LRUCache obj = new LRUCache(capacity);
* int param_1 = obj.get(key);
* obj.put(key,value);
*/
标签:Node,map,缓存,LeetCode146,int,LRU,key,public,LRUCache 来源: https://www.cnblogs.com/alwayszzj/p/15420274.html