LRU Cache

Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.

get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.

set(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.

struct cacheNode
    {
        int key;
        int data;
    };

class LRUCache{
public:
    
    
    LRUCache(int capacity) 
    {
        size = capacity;
    }
    
    int get(int key) 
    {
        if( cacheMap.find(key) != cacheMap.end() )
        {
            list<cacheNode>:: iterator it = cacheMap[key];
            cacheList.splice(cacheList.begin(), cacheList, it);
            cacheMap[key] = cacheList.begin();
            return cacheList.begin()->data;
        }
        else
            return -1;
    }
    
    void set(int key, int value) 
    {
        if( cacheMap.find(key) != cacheMap.end() )
        {
            list<cacheNode>::iterator it = cacheMap[key];
            cacheList.splice(cacheList.begin(), cacheList, it);
            cacheMap[key] = cacheList.begin();
            cacheList.begin()->data = value;
        }
        
        else
        {
            if(cacheList.size() == size)
            {
                cacheMap.erase(cacheList.back().key);
                cacheList.pop_back();
            }
            
            cacheNode node;
            node.key = key;
            node.data = value;
            cacheList.push_front(node);
            cacheMap[key] = cacheList.begin();
        }
    }
    
private:
    int size;
    list<cacheNode> cacheList;
    unordered_map<int, list<cacheNode>::iterator> cacheMap;
};