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460. LFU Cache(unoptimized).cpp
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460. LFU Cache(unoptimized).cpp
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#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define endl "\n"
#define fast_io ios::sync_with_stdio(false); cin.tie(0);
#define file_io freopen("input.txt", "r", stdin); \
freopen("output.txt", "w", stdout);
#define all(x) begin(x), end(x)
#define debug(x) cerr <<"Line "<< __LINE__ <<" : "<< #x " = "<< x <<endl;
template<typename T, typename TT>
ostream& operator<<(ostream &os, const pair<T, TT> &t) { return os<<"("<<t.first<<", "<<t.second<<")"; }
template<typename T>
ostream& operator<<(ostream& os, const vector<T> &t) { for(auto& i: t) os<<i<<" "; return os; }
struct Node {
int key, val, cnt;
Node* prev, *next;
Node(int k, int v) {
key = k, val = v, cnt = 0;
prev = next = nullptr;
}
Node(Node* node) {
this->key = node->key, val = node->val, cnt = node->cnt;
prev = next = nullptr;
}
~Node() {key = val = cnt = 0; prev = next = nullptr;}
};
struct DLList {
Node *head, *tail;
int len;
DLList() {
head = new Node(-1, -1);
tail = new Node(-1, -1);
head->next = tail, tail->prev = head;
len = 0;
}
void addFirst(Node* node) {
++len;
node->prev = head;
node->next = head->next;
head->next->prev = node;
head->next = node;
}
void remove(Node* node) {
Node *p = node->prev, *n = node->next;
p->next = n, node->prev = nullptr;
n->prev = p, node->next = nullptr;
--len;
}
void removeTail() {
Node* node = tail->prev;
remove(node);
delete node;
node = nullptr;
}
void printList() {
cout << "List Size: " << len << endl;
for(Node* n = head->next; n != tail; n = n->next) {
cout << "(" << n->key << ", " << n->val << ") ";
}
cout << endl;
}
~DLList() {
Node* c = head, *cc = nullptr;
while(c) {
cc = c->next;
delete c;
c = cc;
}
c = cc = head = tail = nullptr;
len = 0;
}
};
class LFUCache {
unordered_map<int, Node*> nodeMap;
unordered_map<int, DLList*> freqMap;
unordered_map<int, unordered_map<int, Node*>> freqNodeMap;
size_t size;
int maxFreq, cap;
public:
LFUCache(int capacity) {
cap = capacity;
size = 0, maxFreq = 0;
}
int get(int key) {
//not found
if(nodeMap.find(key) == nodeMap.end()) return -1;
Node* node = nodeMap[key];
int prevfreq = node->cnt, nextfreq = node->cnt+1;
if(freqMap.find(prevfreq) == freqMap.end()) freqMap[prevfreq] = new DLList();
if(freqMap.find(nextfreq) == freqMap.end()) freqMap[nextfreq] = new DLList();
DLList *prevList = freqMap[prevfreq], *nextList = freqMap[nextfreq];
//remove copy of node from prev freq
int v = node->val;
Node* freqNode = freqNodeMap[prevfreq][key];
freqNodeMap[prevfreq][key] = nullptr;
freqNodeMap[prevfreq].erase(key);
prevList->remove(freqNode); delete freqNode; freqNode = nullptr;
//adjust and add node copy in next freq
maxFreq = max(maxFreq, nextfreq);
freqNode = new Node(key, v); freqNode->cnt = nextfreq;
nextList->addFirst(freqNode);
freqNodeMap[nextfreq][key] = freqNode;
nodeMap[key] = freqNode;
return freqNode->val;
}
void put(int key, int value) {
if(cap) {
//already has the key/value pair
if(nodeMap.find(key) != nodeMap.end()) {
nodeMap[key]->val = value;
this->get(key);
return;
} else {
Node* node = new Node(key, value);
if(freqMap.find(1) == freqMap.end())
freqMap[1] = new DLList();
DLList* dlist = freqMap[1];
dlist->addFirst(node), ++size;
node->cnt = 1;
freqNodeMap[1][key] = node;
if(size > (size_t)cap) {
Node* dnode;
if(dlist->len > 1) {
dnode = dlist->tail->prev;
freqNodeMap[1].erase(dnode->key);
nodeMap.erase(dnode->key);
dlist->removeTail();
dnode = nullptr;
}
else {
for(int f = 2; f <= maxFreq; ++f) {
if(freqMap.find(f) != freqMap.end() && freqMap[f]->len > 0) {
dnode = freqMap[f]->tail->prev;
freqNodeMap[f].erase(dnode->key);
nodeMap.erase(dnode->key);
freqMap[f]->removeTail();
dnode = nullptr;
break;
}
}
}
--size;
}
nodeMap[key] = node;
}
}
}
~LFUCache() {
for(int f = 1; f <= maxFreq; ++f) {
freqNodeMap[f].clear();
delete freqMap[f];
freqMap[f] = nullptr;
}
freqMap.clear();
nodeMap.clear();
}
};
/**
* Your LFUCache object will be instantiated and called as such:
* LFUCache* obj = new LFUCache(capacity);
* int param_1 = obj->get(key);
* obj->put(key,value);
*/
int main(int argc, char** argv) {
fast_io
LFUCache* cache = new LFUCache( 2 /* capacity */ );
cache->put(1, 1);
cache->put(2, 2);
cout << cache->get(1) << endl; // returns 1
cache->put(3, 3); // evicts key 2
cout << cache->get(2) << endl; // returns -1 (not found)
cache->put(4, 4); // evicts key 1
cout << cache->get(1) << endl; // returns -1 (not found)
cout << cache->get(3) << endl; // returns 3
cout << cache->get(4) << endl; // returns 4
delete cache;
cache = nullptr;
return 0;
}