哈弗曼編碼的java實現

import java.util.*;

/**
 * Created by lipu on 17-6-28.
 */

class Node {
    Character c;
    int power;
    Node left = null;
    Node right = null;
    boolean isC = false;

    String s = null;

    Node(Character c, int power, Node left, Node right, boolean isC) {
        this.c = c;
        this.power = power;
        this.left = left;
        this.right = right;
        this.isC = isC;
    }

    int getPower() {
        return power;
    }

    void putString(String s) {
        this.s = s;
    }

}

public class huffman {

    public static void main(String[] args) {

        PriorityQueue<Node> q = new PriorityQueue<Node>(100, new Comparator<Node>() {
            @Override
            public int compare(Node n1, Node n2) {
                return n1.getPower() - n2.getPower();
            }
        });

        String s = "beep boop beer!";
        Map<Character, Integer> m = new HashMap<>();
        for (int i = 0; i < s.length(); i++) {
            if (m.get(s.charAt(i)) != null) {
                m.put(s.charAt(i), m.get(s.charAt(i)) + 1);//= =蘭黛嗎
            } else {
                m.put(s.charAt(i), 1);
            }
        }

        for (char fuck : m.keySet()) {
            q.add(new Node(fuck, m.get(fuck), null, null, false));
        }//優先隊列已按照power大小存儲完畢


        while (q.size() != 1) {
            Node a = q.remove();
            Node b = q.remove();
            Node c = new Node(null, a.getPower() + b.getPower(), a, b, true);
            q.add(c);
        }



        Node root = q.remove();//root即爲整個二叉樹的根節點



        System.out.println(root.getPower());
        Map<Character, String> res = new HashMap<>();
        Queue<Node> floor = new LinkedList<>();
        Node a = root.left;
        a.putString("0");
        Node b = root.right;
        b.putString("1");
        floor.add(a);
        floor.add(b);
        while (!floor.isEmpty()) {
            Node x = floor.remove();
            if (x.left == null) {//如果是子節點，就表明這是要存到結果裏的節點(根據哈弗曼數的性質，左子樹爲空則右子樹一定爲空)
                res.put(x.c, x.s);
            } else {//如果不是子節點
                x.left.putString(x.s + "0");
                floor.add(x.left);
                x.right.putString(x.s + "1");
                floor.add(x.right);
            }
        }

        for (Character c : res.keySet()) {
            System.out.print(c + " : ");
            System.out.println(res.get(c));
        }

    }


}