[数据结构与算法]二叉树递归遍历

import java.util.Arrays;
import java.util.LinkedList;

public class MyTree {
    public static Node createTree(LinkedList<Integer> list){
        Node node = null;
        if(list == null||list.isEmpty()){
            return null;
        }
        Integer date = list.removeFirst();
        if(date != null){
            node = new Node(date);
            node.leftchildren = createTree(list);
            node.rightchildren = createTree(list);
        }
        return node;
    }

    private static class Node{
        private Integer date;
        private Node leftchildren;
        private Node rightchildren;
        public Node(Integer date){
            this.date = date;
        }
    }

    public static void preShowTree(Node node){
        if(node == null){
            return;
        }
        System.out.print(node.date+" ");
        preShowTree(node.leftchildren);
        preShowTree(node.rightchildren);
    }

    public static void inShowTree(Node node){
        if(node == null){
            return;
        }
        preShowTree(node.leftchildren);
        System.out.print(node.date+" ");
        preShowTree(node.rightchildren);
    }

    public static void endShowTree(Node node){
        if(node == null){
            return;
        }
        preShowTree(node.leftchildren);
        preShowTree(node.rightchildren);
        System.out.print(node.date+" ");
    }

    public static void main(String[] args) {
        LinkedList<Integer> list = new LinkedList<>(Arrays.asList(new Integer[]{1,2,5,null,8,null,7}));
        Node treenode = createTree(list);
        System.out.println("前序遍历\n");
        preShowTree(treenode);
        System.out.println("中序遍历\n");
        inShowTree(treenode);
        System.out.println("后序遍历\n");
        endShowTree(treenode);
    }
}