146. LRU Cache

This structure is the inside a double linked list and map, the Key&dlinkedlistnode correspondence, do not have to search again

1  Public classLRUCache {2     classNode {3         intkey;4         intvalue;5 Node pre;6 Node Post;7     }8     9     Private intcount;Ten     Private intcapacity; One     PrivateMap<integer, node>map; A     PrivateNode head, tail; -      -      PublicLRUCache (intcapacity) { the          This. Capacity =capacity; -          This. Count = 0; -Map =NewHashmap<integer, node>(); -Head =NewNode (); +Head.pre =NULL; -Tail =NewNode (); +Head.post =tail; ATail.pre =head; atTail.post =NULL; -     } -      -     Private voidRemoveNode (node node) { -Node Prenode =Node.pre; -Node Postnode =Node.post; inPrenode.post =Postnode; -Postnode.pre =Prenode; to     } +      -     Private voidAddNode (node node) { theNode.pre =head; *Node.post =Head.post; $Head.post.pre =node;Panax NotoginsengHead.post =node; -     } the      +     PrivateNode Poll () { ANode Prenode =Tail.pre; the          This. RemoveNode (Prenode); +         returnPrenode; -     } $      $     Private voidMovenodetohead (node node) { -          This. RemoveNode (node); -          This. AddNode (node); the     } -     Wuyi      Public intGetintkey) { theNode node =Map.get (key); -         if(Node! =NULL) { Wu              This. Movenodetohead (node); -             returnNode.value; About         } $         return-1; -     } -      -      Public voidSetintKeyintvalue) { A         if( This. Map.containskey (Key)) { +Node node =Map.get (key); theNode.value =value; -              This. Movenodetohead (node); $}Else { theNode node =NewNode (); theNode.key =key; theNode.value =value; the              This. Map.put (key, node); -count++; in              This. AddNode (node); the             if(Count >capacity) { theNode Tailnode = This. Poll (); About                  This. Map.Remove (Tailnode.key); thecount--; the             }  the         } +     } -}

A little longer buy-in will find that they are riddled with mistakes:

1. See the type of return, get method return is int, do not return to node

2. Function name Variable name figure out

It is worth noting that the constructor inside the LRU, the 21st line, to pay attention to create tail, and then Head.post point to the past!! It's crazy to find this bug!!!.

146. LRU Cache