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 left;
    public TreeNode right;
    public TreeNode(char val){
        this.val = val;
    }
}


public class Main {
    
    public static int i = 0;
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String str = in.nextLine();
            TreeNode Targetroot = createTree(str);
            inOrder(Targetroot);
        }
    }
    public static TreeNode createTree(String str){
        char ch = str.charAt(i);
        TreeNode newroot = null;
        if(ch != '#'){
            newroot = new TreeNode(ch);
            i++;
            newroot.left = createTree(str);
            newroot.right = createTree(str);
        }else{
            i++;
        }
        return newroot;
    }
    public static void inOrder(TreeNode root){
        if(root == null) return;
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }
}