O (1) LRU strategy cache implementation for read-write time complexity

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespacealgorithms{ Public classlruimplementation {Internal classCachenode {InternalCachenode Next =NULL; InternalCachenode Previous =NULL; Internal Objectvalue; Internal stringkey; InternalCachenode (stringKeyObjectval) {                 This. Key =key;  This. value=Val; }        }        Privatedictionary<string, cachenode> values =NULL; Private intSize =0; PrivateCachenode first; PrivateCachenode last;  PublicLruimplementation (intsize) {             This. Size =size;  This. Values =Newdictionary<string, cachenode>(size);  This. First = This. Last =NULL; }         Public intValuecount {Get            {                return  This. Values.            Count; }        }         Public string[] Keys {Get             {                if( This. first! =NULL) {List<string> keylist =Newlist<string>(); Cachenode node= This. First;  Do{keylist.add (Node.key); Node=node.                    Next; }  while(Node! =NULL); returnKeylist.toarray (); }                return NULL; }        }        Private voidRemovelrunode () {if( This. Last! =NULL)            {                 This. values. Remove ( This. Last.key);  This. Last = This. Last.                Previous;  This. Last. Next =NULL; }        }         Public voidAddValue (stringKeyObjectvalue) {cachenode node=NULL; if( This. Values. ContainsKey (key)) {node= This. Values[key]; Node.value=value; if(Node! = This. First) {                    if(node. Next! =NULL) {node. Next.previous=node.                    Previous; }                    if(node. Previous! =NULL) {node. Previous.next=node.                    Next; }                }            }            Else{node=NewCachenode (key, value); if( This. values. Count >= This. Size) {                     This.                Removelrunode (); }                 This. Values.            ADD (key, node); }            if( This. first! =NULL&& This. first! =node) {node. Next= This. First;  This. First. Previous =node; }             This. First =node; if( This. last = =NULL)            {                 This. Last =node; }        }         Public ObjectTryGetValue (stringkey) {            if( This. Values. ContainsKey (key)) {Cachenode node= This. Values[key]; if(Node! = This. First) {                    if(node. Previous! =NULL) {node. Previous.next=node.                    Next; }                    if(node. Next! =NULL) {node. Next.previous=node.                    Previous; }                     This. First. Previous =node; Node. Next= This. First;  This. First =node; }                                return  This. First.value; }            return NULL; }         Public stringgetbuffercontent () {return string. Join (",", This.        Keys); }    }}

The main use of Hashtable (Dictionary) and linked list implementation, can achieve O (1) Read and write time complexity.

Test code:

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespacealgorithms{classProgram {Static voidMain (string[] args) {             Do            {                intCacheSize =0; BOOLIsValid =true;  Do{Console.WriteLine ("Input Cache Size:"); IsValid=int. TryParse (Console.ReadLine (), outcacheSize); if(CacheSize <=0) {IsValid=false; }                    if(!isValid) {Console.WriteLine ("Invalid value."); }                }                  while(!isValid); Lruimplementation LRU=Newlruimplementation (cacheSize); Random Rand=NewRandom ();  Do{Console.WriteLine ("Input Key:"); stringKey =Console.ReadLine (); Console.WriteLine ("Input Value:"); stringval =Console.ReadLine (); Lru.                    AddValue (Key, Val); Console.WriteLine ("Cache Content:"); Console.foregroundcolor=Consolecolor.green; Console.WriteLine (LRU.                    Getbuffercontent ());                    Console.resetcolor (); intRandindex = Rand. Next (0Lru. Valuecount-1); Console.WriteLine ("Try to query the {0}th value.", Randindex); Lru. TryGetValue (LRU.                    Keys[randindex]); Console.WriteLine ("Cache Content:"); Console.foregroundcolor=Consolecolor.green; Console.WriteLine (LRU.                    Getbuffercontent ());                Console.resetcolor (); }  while(true); }              while(true);        }    }}

O (1) LRU strategy cache implementation for read-write time complexity