题目

给你一棵二叉树的根节点 root ，翻转这棵二叉树，并返回其根节点。

解法一

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            TreeNode left = node.left;
            TreeNode right = node.right;
            if (right != null) {
                queue.offer(right);
            }
            if (left != null) {
                queue.offer(left);
            }
            node.left = right;
            node.right = left;
        }
        return root;
    }
}

解法二

思路

迭代

代码

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if (root == null) {
            return null;
        }
        TreeNode left = invertTree(root.left);
        TreeNode right = invertTree(root.right);
        root.left = right;
        root.right = left;
        return root;
    }
}