leetcode LRU Cache

来源：互联网发布：软件需求分析阶段编辑：程序博客网时间：2024/05/29 16:54

一看到这个就想到链表了，不过写的过程还是略微曲折。

没想到的是最后居然TLE。在leetcode上看到一个很漂亮的代码，但是本地测试耗时是我的近3倍，不知道为什么这个能AC。

我的代码时间复杂度也就是O(n)啊。。。

struct Node{public:int val;Node * next;Node(int v) :val(v), next(NULL) {}};class MyLRUCache{private:Node *khead;Node *vhead;int capa, count;public:MyLRUCache(int capacity) {khead = NULL;vhead = NULL;capa = capacity;count = 0;}int get(int key, bool isSet = false) {if (count == 0)return -1;if (khead->val == key)return vhead->val;if (count == 1)return -1;int i = 1;Node *p = khead, *tmp = p;while (i < count){if (p->next->val == key){break;}i++;tmp = p;p = p->next;}if (i == count){if (isSet && count == capa){p->next = khead;khead = p;tmp->next = NULL;p = vhead;while (p->next){tmp = p;p = p->next;}p->next = vhead;vhead = p;tmp->next = NULL;}return -1;//not found}//adjust key listtmp = p->next->next;p->next->next = khead;khead = p->next;p->next = tmp;//adjust value listNode *v = vhead;int j = 0;while (j++ < i - 1)v = v->next;tmp = v->next;v->next = tmp->next;tmp->next = vhead;vhead = tmp;return vhead->val;}void set(int key, int value) {if (capa == 0)return;if (count == 0){khead = new Node(key);vhead = new Node(value);count++;return;}int res = get(key, true);if (count < capa && res == -1){Node *k = new Node(key);Node *v = new Node(value);k->next = khead;v->next = vhead;khead = k;vhead = v;count++;return;}khead->val = key;vhead->val = value;return;}};

//别人的代码class LRUCache{public:LRUCache(int capacity) {this->capacity = capacity;}int get(int key) {if (mp.count(key)>0){moveToEnd(key);return mp[key];}return -1;}void set(int key, int value) {if (mp.count(key)>0){mp[key] = value;moveToEnd(key);}else if (mp.size()<capacity){mp[key] = value;l.push_back(key);pos[key] = getLast(l);}else{mp.erase(l.front());l.pop_front();mp[key] = value;l.push_back(key);pos[key] = getLast(l);}}//change key's literator to list's end in posvoid moveToEnd(int key){l.erase(pos[key]);l.push_back(key);list<int>::iterator i = l.end();i--;pos[key] = i;}list<int>::iterator getLast(list<int> &l){auto it = l.end();it--;return it;}private:map<int, int> mp;map<int, list<int>::iterator> pos;list<int> l;int capacity;};

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