代码如下:
package HuffmanTree;import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;public class HuffmanTree {private class TreeNode{private int val;private TreeNode left;private TreeNode right;public TreeNode(){val = 0;left = right = null;}public TreeNode(int e){val = e;left = right = null;}}private TreeNode data[];private int size;private TreeNode TreeRoot;public HuffmanTree(int n){TreeRoot = null;data = new TreeNode[n+1];Scanner sc = new Scanner(System.in);for (int i = 1;i<=n;i++){TreeNode t = new TreeNode(sc.nextInt());data[i] = t;size++;}for (int i = size/2;i>0;i--){percDown(i);}}private void percDown(int p){TreeNode x = data[p];int parent,child;for (parent = p;parent*2 <=size;parent = child){child = 2*parent;if (child!=size && data[child].val > data[child+1].val){child++;}if (x.val <= data[child].val) break;else data[parent] = data[child];}data[parent] = x;}private TreeNode deleteMin(){TreeNode minData = data[1];TreeNode x = data[size--];int parent,child;for (parent = 1;parent*2<=size;parent = child){child = 2*parent;if (child!=size && data[child].val > data[child+1].val){child++;}if (x.val <= data[child].val) break;else data[parent] = data[child];}data[parent] = x;return minData;}private void insertHeap(TreeNode e){int i = ++size;for (;i>1 && data[i/2].val > e.val ;i = i/2){data[i] = data[i/2];}data[i] = e;}public void buildHuffmanTree(){TreeNode t;int cnt = size;for (int i = 1;i<cnt;i++){t = new TreeNode();t.left = deleteMin();t.right = deleteMin();t.val = t.left.val+t.right.val;insertHeap(t);}TreeRoot = deleteMin();}private void printNode(TreeNode e){System.out.print(e.val+" ");if (e.left!=null) System.out.print("left = "+e.left.val+" ");else System.out.print("left = null ");if (e.right!=null) System.out.print("right = "+e.right.val+" ");else System.out.print("right = null ");System.out.println();}public void levelOrder(){Queue<TreeNode> q = new LinkedList<>();q.add(TreeRoot);while(!q.isEmpty()){TreeNode t = q.poll();printNode(t);if (t.left!=null) q.add(t.left);if (t.right!=null) q.add(t.right);}}public void codeHuffmanTree(){ArrayList<Integer> arrays = new ArrayList<>();if (TreeRoot==null){System.out.println(arrays);return ;}dfsNode(TreeRoot,arrays);}private void dfsNode(TreeNode root,ArrayList<Integer> arrays){if (root.left==null && root.right==null){System.out.println(root.val+" = "+arrays);return ;}if (root.left!=null){arrays.add(0);dfsNode(root.left,arrays);arrays.remove(arrays.lastIndexOf(0));}if (root.right!=null){arrays.add(1);dfsNode(root.right,arrays);arrays.remove(arrays.lastIndexOf(1));}}}测试类如下:
package HuffmanTree;public class TestHuffmanTree {public static void main(String[] args){HuffmanTree hf = new HuffmanTree(7);hf.buildHuffmanTree();hf.levelOrder();hf.codeHuffmanTree();}
}
时间的非递归的过程，将该树每个结点的关键字输出（算法导论第三版第十章10.4-5）)
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