Java递归添加到列表

import java.util.ArrayList;
import java.util.List;

class TreeNode {
    int value;
    List<TreeNode> children;

    TreeNode(int value) {
        this.value = value;
        this.children = new ArrayList<>();
    }
}

public class RecursiveListAddition {
    public static void main(String[] args) {
        // 创建一个简单的树结构
        TreeNode root = new TreeNode(1);
        TreeNode child1 = new TreeNode(2);
        TreeNode child2 = new TreeNode(3);
        root.children.add(child1);
        root.children.add(child2);
        TreeNode child1_1 = new TreeNode(4);
        child1.children.add(child1_1);

        List<Integer> result = new ArrayList<>();
        addValuesToList(root, result);

        // 打印结果
        System.out.println(result); // 应该输出 [1, 2, 4, 3]
    }

    private static void addValuesToList(TreeNode node, List<Integer> list) {
        // 基本情况：如果节点为空，则不做任何操作
        if (node == null) return;

        // 将当前节点的值添加到列表中
        list.add(node.value);

        // 递归步骤：对每个子节点调用此方法
        for (TreeNode child : node.children) {
            addValuesToList(child, list);
        }
    }
}