洛谷P1305 新二叉树

Java 代码

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        char arr[][] = new char[n][3];
        for (int i = 0; i < n; i++) {
            String str=sc.next();
            char arr1[]=str.toCharArray();
            for (int j = 0; j < 3; j++) {
                arr[i][j]=arr1[j];
            }
        }
        TreeNode Root = null;
        Root = creat(arr, 0, 0);
        bianli(Root);
    }

    // 数据结构
    static class TreeNode {
        char val;
        public TreeNode left;
        public TreeNode right;

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

    // 创建二叉树
    public static TreeNode creat(char arr[][], int i, int j) {
        if (i >= arr.length || j >= 3 ||arr[i][j] == '*') {
            return null;
        }
        TreeNode node = new TreeNode(arr[i][j]);

        for (int k = 0; k < arr.length; k++) {
            if(arr[i][j]==arr[k][0]){
                i=k;
                break;
            }
        }
        node.left = creat(arr, i, 1);
        node.right = creat(arr, i, 2);
        return node;
    }

    //遍历二叉树
    public static void bianli(TreeNode node){
        if (node==null) return;
        System.out.print(node.val);
        bianli(node.left);
        bianli(node.right);
    }
}

下面是失败的尝试

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        char arr[][] = new char[n][3];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < 3; j++) {
                arr[i][j] = sc.next().charAt(0);
            }
        }
        TreeNode Root = null;
        Root = creat(arr, 0, 0);
        bianli(Root);
    }

    // 数据结构
    static class TreeNode {
        char val;
        public TreeNode left;
        public TreeNode right;

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

    // 创建二叉树
    public static TreeNode creat(char arr[][], int i, int j) {
        if (i >= arr.length || j >= 3 ||arr[i][j] == '*') {
            return null;
        }
        TreeNode node = new TreeNode(arr[i][j]);

        for (int k = 0; k < arr.length; k++) {
            if(arr[i][j]==arr[k][0]){
                i=k;
                break;
            }
        }
        node.left = creat(arr, i, 1);
        node.right = creat(arr, i, 2);
        return node;
    }

    //遍历二叉树
    public static void bianli(TreeNode node){
        if (node==null) return;
        System.out.print(node.val);
        bianli(node.left);
        bianli(node.right);
    }
}