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Copy pathLRU Cahe.cpp
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Copy pathLRU Cahe.cpp
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127 lines (105 loc) · 3.77 KB
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//ya no list only pointer manip beats 99.96 percent runtime as well as 99.04 memory usage
//also tle is fixed
class LRUCache {
public:
struct Node{
Node(Node* prev , Node * next, int value,int key):s_prev(prev),s_next(next),s_value(value),s_key(key){}
int s_value;
int s_key;
Node * s_next;
Node * s_prev;
};
LRUCache(int capacity):m_capacity(capacity),m_key_val(),m_lru(nullptr),m_mru(nullptr){
ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
}
int get(int key) {
if(m_key_val.find(key) != m_key_val.end()){
Node * elm = m_key_val[key];
if(m_mru != m_lru){
if(m_mru != m_key_val[key]){
if(elm->s_prev == nullptr){
m_lru = m_lru->s_next;
m_lru->s_prev = nullptr;
}
else{
elm->s_prev->s_next = elm->s_next;
elm->s_next->s_prev = elm->s_prev;
}
m_mru->s_next = elm;
elm->s_prev = m_mru;
m_mru = elm;
elm->s_next = nullptr;
}
}
return m_mru->s_value;
}
else
return -1;
}
void put(int key, int value) {
if(m_key_val.find(key) != m_key_val.end()){
m_key_val[key]->s_value = value;
Node * elm = m_key_val[key];
if(m_mru != m_lru){
if(m_mru != m_key_val[key]){
if(elm->s_prev == nullptr){
m_lru = m_lru->s_next;
m_lru->s_prev = nullptr;
}
else{
elm->s_prev->s_next = elm->s_next;
elm->s_next->s_prev = elm->s_prev;
}
m_mru->s_next = elm;
elm->s_prev = m_mru;
m_mru = elm;
elm->s_next = nullptr;
}
}
}
else if(m_capacity > 0){
Node * nPtr = new Node(nullptr,nullptr,value,key);
m_key_val[key] = nPtr;
if(m_mru == nullptr && m_lru == nullptr){
m_mru = nPtr;
m_lru = nPtr;
}
else{
m_mru->s_next = nPtr;
nPtr->s_prev = m_mru;
m_mru = nPtr;
}
m_capacity--;
}
else{ //eviction
m_key_val.erase(m_lru->s_key);
if(m_mru == m_lru){
m_lru->s_key = key;
m_lru->s_value = value;
m_key_val[key] = m_lru;
}
else{
Node* temp = m_lru;
m_lru=m_lru->s_next;
m_lru->s_prev = nullptr;
m_mru->s_next = temp;
temp->s_prev = m_mru;
m_mru = temp;
m_mru->s_next = nullptr;
m_key_val[key] = temp;
temp->s_key = key;
temp->s_value = value;
}
}
}
int m_capacity;
unordered_map<int,Node*>m_key_val;
Node * m_lru;
Node * m_mru;
};
/**
* 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);
*/