数据结构:赫夫曼树

 

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class HuffmanTree {
    public static void main(String[] args) {
        int[] arr = {13, 7, 8, 3, 29, 6, 1};
        Node huff = createHuffmanTree(arr);
        huff.preOrder();
    }

    // 创建赫夫曼树
    public static Node createHuffmanTree(int[] arr){

        List<Node> nodes = new ArrayList<Node>();
        for (int i = 0; i < arr.length; i++) {
            nodes.add(new Node(arr[i]));
        }

        while(nodes.size() > 1) {
            // 排序
            Collections.sort(nodes);

            // 取出权值最小的结点
            Node leftNode = nodes.get(0);
            // 取出权值次小的结点
            Node rightNode = nodes.get(1);
            // 构建一颗新的二叉树
            Node parent = new Node(leftNode.value + rightNode.value);
            parent.left = leftNode;
            parent.right = rightNode;

            // 删除处理过的二叉树
            nodes.remove(leftNode);
            nodes.remove(rightNode);

            // 将parent加入到nodes
            nodes.add(parent);
        }

        System.out.println(nodes);
        return nodes.get(0);
    }
}

class Node implements Comparable<Node>{

    int value;  // 结点权值
    Node left;
    Node right;

    // 前序遍历
    public void preOrder(){

        System.out.println(this.value);
        if(null != this.left){
            this.left.preOrder();
        }

        if(null != this.right){
            this.right.preOrder();
        }
    }

    public Node(int value){
        this.value = value;
    }

    @Override
    public String toString() {
        return "Node{" +
                "value=" + value +
                '}';
    }

    @Override
    public int compareTo(Node o) {
        return this.value - o.value;
    }
}