java实现Huffman树

package greedy;import java.util.ArrayList;import java.util.Arrays;import java.util.Comparator;import java.util.HashMap;import java.util.List;public class Huffman {private static final String dir = "ABCDEFGHIJKLMNOPQRSTUVWXYZ.,;/!?abcdefghijklmnopqrstuvwxyz";private static Node[] nodeArray;public static HashMap<Character, String> map = new HashMap<Character, String>();// 存放字符=>编码的key-value对static {nodeArray = new Node[dir.length() * 2 - 1];for (int i = 0; i < dir.length(); i++) {nodeArray[i] = new Node(dir.charAt(i), (int) (100 * Math.random() + 1), 0, -1, -1);}Arrays.sort(nodeArray, 0, dir.length() - 1, new Comparator<Node>() {@Overridepublic int compare(Node o1, Node o2) {return o1.weight - o2.weight;}});initHuffmanTree();}private static void initHuffmanTree() {int initLength = dir.length();for (int i = 0; i < nodeArray.length - 2;) {Node x = nodeArray[i];Node y = nodeArray[i + 1];Node parent = new Node(x.weight + y.weight, i + 1, i);int j = i + 2;while (j < initLength && nodeArray[j].weight <= parent.weight && nodeArray[j].weight != 0)j++;for (int k = initLength; k > j; k--) {if (nodeArray[k - 1].left != -1) {nodeArray[nodeArray[k - 1].left].parent = k;nodeArray[nodeArray[k - 1].right].parent = k;}if ((k - 1) == nodeArray[nodeArray[k - 1].parent].left) {nodeArray[nodeArray[k - 1].parent].left = k;} else if ((k - 1) == nodeArray[nodeArray[k - 1].parent].right) {nodeArray[nodeArray[k - 1].parent].right = k;}nodeArray[k] = nodeArray[k - 1];}if (j < nodeArray.length) {nodeArray[j] = parent;x.parent = j;y.parent = j;}initLength++;i += 2;}for (int i = 0; i < nodeArray.length; i++) {System.out.println(i + "->" + nodeArray[i]);}Node root = nodeArray[nodeArray.length - 1];List<String> codeStack = new ArrayList<String>();List<Node> nodeStack = new ArrayList<Node>();for (;;) {if (root.left != -1) {nodeStack.add(root);root = nodeArray[root.left];codeStack.add("0");} else {String code01 = "";for (int i = 0; i < codeStack.size(); i++)code01 += codeStack.get(i);map.put(root.key, code01);if (root == nodeArray[nodeArray[root.parent].left]) {codeStack.set(codeStack.size() - 1, "1");root = nodeArray[nodeArray[root.parent].right];} else {while (!root.equals(nodeArray[nodeArray.length - 1])&& root == nodeArray[nodeArray[root.parent].right]) {root = nodeStack.remove(nodeStack.size() - 1);codeStack.remove(codeStack.size() - 1);}if (root.equals(nodeArray[nodeArray.length - 1]))break;codeStack.set(codeStack.size() - 1, "1");root = nodeArray[nodeArray[root.parent].right];}}}System.out.println(map);}public static class Node {public char key;public int weight;public int parent;public int right;public int left;public Node(char key, int weight, int parent, int right, int left) {super();this.key = key;this.weight = weight;this.parent = parent;this.right = right;this.left = left;}@Overridepublic String toString() {return "Node [key=" + key + ", weight=" + weight + ", parent=" + parent + ", right=" + right + ", left="+ left + "]";}public Node() {}public Node(char key, int weight, int right, int left) {super();this.key = key;this.weight = weight;this.right = right;this.left = left;}public Node(int weight, int right, int left) {super();this.weight = weight;this.right = right;this.left = left;}public Node(char key, int weight) {this.key = key;this.weight = weight;}}}