https://github.com/emahtab/lru-cache

LRU Cache
https://github.com/emahtab/lru-cache

doubly-linked-list hashmap leetcode lru-cache

Last synced: about 7 hours ago
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LRU Cache

• Host: GitHub
• URL: https://github.com/emahtab/lru-cache
• Owner: eMahtab
• Created: 2020-02-15T16:49:30.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2024-10-29T16:36:53.000Z (3 months ago)
• Last Synced: 2024-12-07T03:14:01.169Z (about 2 months ago)
• Topics: doubly-linked-list, hashmap, leetcode, lru-cache
• Homepage:
• Size: 5.86 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# LRU Cache

## https://leetcode.com/problems/lru-cache

## Implementation :

```java

class LRUCache {

    Map hashtable = new HashMap();

    ListNode head, tail;

    int totalItemsInCache, maxCapacity;

    

    private class ListNode {

      int key, value;

      ListNode next, prev;

    }

    public LRUCache(int capacity) {

      this.totalItemsInCache = 0;

      this.maxCapacity = capacity;

      head = new ListNode();

      tail = new ListNode();

      head.next = tail;

      tail.prev = head;

    }

    

    public int get(int key) {

      ListNode node = hashtable.get(key);

      if (node == null) 

         return -1;

      moveToHead(node);

      return node.value;  

    }

    

    private void moveToHead(ListNode node) {

      removeFromList(node);

      addToFront(node);

    }

    

    private void removeFromList(ListNode node) {

      ListNode prevNode = node.prev;

      ListNode nextNode = node.next;

      prevNode.next = nextNode;

      nextNode.prev = prevNode;

    }

    

    private void addToFront(ListNode node) {

      // Wire up the new node being to be inserted

      node.prev = head;

      node.next = head.next;

      head.next.prev = node;

      head.next = node;

    }

    

    public void put(int key, int value) {

      ListNode node = hashtable.get(key);

      if (node == null) {

        ListNode newNode = new ListNode();

        newNode.key = key;

        newNode.value = value;

        hashtable.put(key, newNode);

        addToFront(newNode);

        totalItemsInCache++;

        if (totalItemsInCache > maxCapacity) {

          ListNode tailNode = tail.prev;

          removeFromList(tailNode);

          hashtable.remove(tailNode.key);

          --totalItemsInCache;

        }

      } else {

        node.value = value;

        moveToHead(node);

      }

    }

}

```

# References :

1. https://www.youtube.com/watch?v=S6IfqDXWa10

2. https://github.com/bephrem1/backtobackswe/blob/master/Linked%20Lists/LRUCache/LRUCache.java