在Java中镜像二叉树

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}

public class BinaryTreeMirror {
    public TreeNode mirrorTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        // 交换左右子树
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;
        
        // 递归处理左右子树
        mirrorTree(root.left);
        mirrorTree(root.right);
        
        return root;
    }
}

import java.util.LinkedList;
import java.util.Queue;

public class BinaryTreeMirror {
    public TreeNode mirrorTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(root);
        
        while (!queue.isEmpty()) {
            TreeNode current = queue.poll();
            
            // 交换左右子树
            TreeNode temp = current.left;
            current.left = current.right;
            current.right = temp;
            
            // 将非空的子节点加入队列
            if (current.left != null) {
                queue.add(current.left);
            }
            if (current.right != null) {
                queue.add(current.right);
            }
        }
        
        return root;
    }
}