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下面是一个C#实现二叉树的层次遍历的例子：
using System; using System.Collections.Generic; public class TreeNode { public int val; public TreeNode left; public TreeNode right; public TreeNode(int val = 0, TreeNode left = null, TreeNode right = null) { this.val = val; this.left = left; this.right = right; } } public class BinaryTree { public List<List<int>> LevelOrder(TreeNode root) { List<List<int>> result = new List<List<int>>(); if (root == null) { return result; } Queue<TreeNode> queue = new Queue<TreeNode>(); queue.Enqueue(root); while (queue.Count > 0) { int levelSize = queue.Count; List<int> levelValues = new List<int>(); for (int i = 0; i < levelSize; i++) { TreeNode node = queue.Dequeue(); levelValues.Add(node.val); if (node.left != null) { queue.Enqueue(node.left); } if (node.right != null) { queue.Enqueue(node.right); } } result.Add(levelValues); } return result; } } class Program { static void Main() { TreeNode root = new TreeNode(3); root.left = new TreeNode(9); root.right = new TreeNode(20); root.right.left = new TreeNode(15); root.right.right = new TreeNode(7); BinaryTree bt = new BinaryTree(); List<List<int>> result = bt.LevelOrder(root); foreach (List<int> level in result) { Console.Write("["); foreach (int val in level) { Console.Write(val + " "); } Console.Write("]"); Console.WriteLine(); } } } 这段代码实现了一个二叉树的层次遍历。通过使用一个队列来辅助遍历，每次遍历一层节点，依次将它们的值存入结果列表中。最后返回结果列表。在Main函数中创建一个二叉树节点并调用LevelOrder方法进行层次遍历。
