Huffman Tree in Java

1  PackageCom.ietree.basic.datastructure.tree;2 3 ImportJava.util.ArrayDeque;4 Importjava.util.ArrayList;5 Importjava.util.List;6 ImportJava.util.Queue;7 8 /**9 * Created by IetreeTen * 2017/5/1 One  */ A  Public classHuffmantree { -  -      Public Static classNode<e> { the E data; -         Doubleweight; - Node leftchild; - Node rightchild; +  -          PublicNode (E data,Doubleweight) { +              This. data =data; A              This. Weight =weight; at         } -  -          PublicString toString () { -             return"Node[data=" + Data + ", weight=" + weight + "]"; -         } -     } in  -      Public Static voidMain (string[] args) { to  +list<node> nodes =NewArraylist<node>(); -Nodes.Add (NewNode ("A", 40)); theNodes.Add (NewNode ("B", 8)); *Nodes.Add (NewNode ("C", 10)); $Nodes.Add (NewNode ("D", 30));Panax NotoginsengNodes.Add (NewNode ("E", 10)); -Nodes.Add (NewNode ("F", 2)); the  +Node root =huffmantree.create (nodes); A System.out.println (Breadthfirst (root)); the  +     } -  $     /** $ * Construction Huffman Tree -      * -      * @paramNodes Node Collection the      * @returnThe root node of the Huffman tree constructed -      */Wuyi     Private StaticNode Create (list<node>nodes) { the  -         //as long as there are more than 2 nodes in the nodes array Wu          while(Nodes.size () > 1) { - QuickSort (nodes); About             //get the two nodes with the least weighted value $Node left = Nodes.get (Nodes.size ()-1); -Node right = Nodes.get (Nodes.size ()-2); -             //To generate a new node, the weight of the new node is the sum of the weights of two child nodes -Node parent =NewNode (NULL, Left.weight +right.weight); A             //make the new node the parent of the two nodes with the least weight +Parent.leftchild =Left ; theParent.rightchild =Right ; -             //Delete the two nodes with the lowest weighted value $Nodes.remove (Nodes.size ()-1); theNodes.remove (Nodes.size ()-1); the             //to add a newly generated parent node to the collection the Nodes.Add (parent); the         } -         //returns the only node in the Nodes collection, which is the root node in         returnNodes.get (0); the     } the  About     //swaps the elements at the I and J indices of the specified array the     Private Static voidSwap (list<node> nodes,intIintj) { the Node tmp; theTMP =Nodes.get (i); + Nodes.set (I, Nodes.get (j)); - Nodes.set (J, TMP); the     }Bayi  the     //implement a quick sort algorithm for sorting nodes the     Private Static voidSubsort (list<node> nodes,intStartintend) { -  -         //need to sort the         if(Start <end) { the             //take the first element as a cutoff value theNode base =nodes.get (start); the             //I search from the left, searching for an index of an element greater than the cutoff value -             inti =start; the             //J Search from the right, search for the index of the element less than the cutoff value the             intj = End-1; the              while(true) {94                 //The index of the element that is greater than the cutoff value is found, or I is already at end the                  while(I < end && Nodes.get (++i). Weight >=base.weight); the                 //Find the index of the element that is less than the cutoff value, or J is at start the                  while(J > Start && nodes.get (--j). Weight <=base.weight);98                 if(I <j) { About swap (nodes, I, j); -}Else {101                      Break;102                 }103             }104 Swap (nodes, start, j); the             //recursive left sub-tree sequence106Subsort (nodes, start, j-1);107             //Recursive right sub-tree sequence108Subsort (nodes, J + 1, end);109         } the     }111  the      Public Static voidQuickSort (list<node>nodes) {113Subsort (nodes, 0, Nodes.size ()-1); the     } the  the     //breadth-First traversal117      Public StaticList<node>Breadthfirst (Node root) {118 119queue<node> queue =NewArraydeque<node>(); -list<node> list =NewArraylist<node>();121         if(Root! =NULL) {122             //put the root element into the queue123 Queue.offer (root);124         } the          while(!Queue.isempty ()) {126             //Add the "tail" element of the queue to the list127 List.add (Queue.peek ()); -Node p =Queue.poll ();129             //If the left Dial hand node is not NULL, add it to the queue the             if(P.leftchild! =NULL) {131 Queue.offer (p.leftchild); the             }133             //If the right child node is not NULL, add it to the queue134             if(P.rightchild! =NULL) {135 Queue.offer (p.rightchild);136             }137         }138         returnlist;139  $     }141 142}

Huffman Tree in Java