哈夫曼树的实现-Java实现

哈夫曼的核心思想在于，wpl最小；

package dataSrtuct.TreeAlgorithm;

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 root=CHuffmanTree(arr);
        preOrder(root);
    }
    public static Node CHuffmanTree(int[] arr){
        List<Node> list=new ArrayList<>();
        for (int val: arr) {
            list.add(new Node(val));
        }
        while (list.size()>1){
            Collections.sort(list);
            Node node=new Node(list.get(0).val+list.get(1).val);
            node.left=list.get(0);
            node.right=list.get(1);
            //注意源码是重新创建了一个数组，所以删除一个元素，整体是相当与前移了，只需重复删除第一个即可；
            list.remove(0);
            list.remove(0);
            list.add(node);
        }
        return list.get(0);
    }
    public static void preOrder(Node node){
        if (node!=null)
            node.preOrder(node);
        else
            System.out.println("是空树");
    }
}
class Node implements Comparable<Node>{
    int val;
    Node left;
    Node right;
    public Node(int val){
        this.val=val;
    }

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

    @Override
    public String toString() {
        return "Node{" +
                "val=" + val +
                '}';
    }
    public void preOrder(Node node){
        System.out.println(node.val);
        if (node.left!=null)
            preOrder(node.left);
        if (node.right!=null)
            preOrder(node.right);
    }
}