题解 | #二叉树遍历#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
class TreeNode {
    public char val;
    public TreeNode leftChild;
    public TreeNode rightChild;

    public TreeNode(char val) {
        this.val = val;
    }
}
public class Main {
    public static int i = 0;
    public static TreeNode createTree(String s){
        TreeNode root = null;
        //1.遍历字符串s
        if(s.charAt(i) != '#'){
            //2.根据前序遍历创建二叉树
            root = new TreeNode(s.charAt(i));
            i++;
            root.leftChild = createTree(s);
            root.rightChild = createTree(s);
        }else{
            i++;
        }
        //3.返回根节点

        return root;
    }
    public static void inOrder(TreeNode root){
        if(root == null){
            return;
        }
        inOrder(root.leftChild);
        System.out.print(root.val+" ");
        inOrder(root.rightChild);
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) {
            String str = in.nextLine();
            TreeNode root = createTree(str);
            inOrder(root);
        }
    }
}