c语言实现lur算法
时间: 2024-07-12 21:00:38 浏览: 114
基于C语言实现的两种常见页面置换算法(OPT,LRU)
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LUR(Least Recently Used)算法,也称为最近最少使用算法,是一种常用的内存管理策略,主要用于淘汰系统中的缓存或者页面,以释放空间给新的数据。在C语言中实现LUR算法,主要是模拟LRU缓存的逻辑,通常会涉及到链表和哈希表的数据结构。
以下是一个简单的C语言版LRU缓存实现思路:
1. 定义一个LRUCache类,包含一个大小为capacity的链表和哈希表:
```c
typedef struct Node {
int key;
int value;
struct Node *prev, *next;
} Node;
typedef struct LRUCache {
int capacity;
Node *head, *tail;
unordered_map<int, Node*> cache;
} LRUCache;
```
2. 初始化LRUCache:
```c
LRUCache *initLRUCache(int capacity) {
LRUCache *cache = (LRUCache*)malloc(sizeof(LRUCache));
cache->capacity = capacity;
cache->head = cache->tail = NULL;
return cache;
}
```
3. 插入操作(删除最近最少使用的节点并添加到头部):
```c
void insertNode(LRUCache *cache, int key, int value) {
Node *node = new Node{key, value, NULL, NULL};
if (cache->cache.find(key) == cache->cache.end()) {
if (cache->tail) {
node->next = cache->tail;
cache->tail->prev = node;
cache->tail = node;
} else {
cache->head = node;
}
cache->cache[key] = node;
if (cache->size > cache->capacity) {
Node *temp = cache->head;
cache->head = temp->next;
delete temp;
}
} else {
Node *oldNode = cache->cache[key];
removeNode(oldNode);
insertNode(cache, key, value);
}
}
```
4. 删除操作(从链表和哈希表中移除指定节点):
```c
void removeNode(Node *node) {
if (node->prev)
node->prev->next = node->next;
else
cache->head = node->next;
if (node->next)
node->next->prev = node->prev;
else
cache->tail = node->prev;
delete node;
cache->cache.erase(node->key);
}
```
5. 获取值(检查哈希表,如果存在则移到头部):
```c
int get(LRUCache *cache, int key) {
auto it = cache->cache.find(key);
if (it == cache->cache.end())
return -1;
Node *node = it->second;
removeNode(node);
insertNode(cache, key, node->value);
return node->value;
}
```
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