算法——中序遍历二叉树（递归）

应该为2-1-3-4

• 树节点：

public class TreeNode {
    int no;
    String name;
    TreeNode left;
    TreeNode right;

    public TreeNode(int no, String name) {
        this.no = no;
        this.name = name;
    }

    @Override
    public String toString() {
        return "{" + "no=" + no + ", name='" + name + ''' + '}';
    }
}

• 二叉树

public class BinaryTree {
    //二叉树根节点
    TreeNode head;

    public BinaryTree(TreeNode head) {
        this.head = head;
    }
}

• 中序遍历算法：

public class MidOrder {
    public static void main(String[] args) {
        TreeNode head = new TreeNode(1, "宋江");
        TreeNode node2 = new TreeNode(2, "吴用");
        TreeNode node3 = new TreeNode(3, "卢俊");
        TreeNode node4 = new TreeNode(4, "林冲");
        head.left = node2;
        head.right = node3;
        node3.right = node4;
        BinaryTree bt = new BinaryTree(head);
        mid(bt);
    }

    public static void mid(BinaryTree bt) {
        if (bt.head == null) {
            System.out.println("二叉树为空！");
            return;
        }
        //调用遍历算法
        order(bt.head);
    }

    public static void order(TreeNode node) {

        //左递归
        if (node.left != null)
            order(node.left);

        //打印二叉树
        System.out.println(node);

        //右递归
        if (node.right != null)
            order(node.right);
    }
}