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LRU_Cache.java
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LRU_Cache.java
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import java.util.*;
public class lruCatche {
public static void main(String[] args) {
LRU lru = new LRU(3);
lru.put(1, 10);
lru.put(2, 20);
lru.put(3, 30);
System.out.println( lru.get(1) );
lru.put(1, 15);
System.out.println( lru.get(1) );
System.out.println( lru.get(2) );
//System.out.println(lru.map.size());
//System.out.println(lru.tail.prev.key);
lru.put(4, 40);
System.out.println( lru.get(3) );
System.out.println( lru.get(4) );
}
}
class Node{
int data;
int key;
Node next;
Node prev;
Node(int key,int data){
this.data =data;
this.key =key;
this.next = null;
this.prev =null;
}
}
class LRU{
int capacity;
Node head = new Node(-1, -1);
Node tail = new Node(-1,-1);
HashMap<Integer,Node> map = new HashMap<>();
LRU(int cap){
this.capacity = cap;
head.next = tail;
tail.prev = head;
}
int get(int key){
if(map.containsKey(key)){
Node node = map.get(key);
deleteNode(node);
insert(node);
return map.get(key).data;
}
return -1;
}
void put(int key , int val){
if(map.containsKey(key)){
deleteNode(map.get(key));
map.remove(key);
}
else if(map.size()==capacity){
map.remove(tail.prev.key);
deleteNode(tail.prev);
}
Node node = new Node(key, val);
insert(node);
map.put(key, node);
}
void insert(Node node){
node.next = head.next;
node.next.prev = node;
head.next = node;
node.prev = head;
}
void deleteNode(Node node){
Node delN = node.next;
Node delP = node.prev;
delP.next = delN;
delN.prev = delP;
}
}