leetcode226. 翻转二叉树(Java)

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if (root == null) return null;

        swap(root);//交换结点的时候 用的是root 这样才能改变root的结构
        invertTree(root.left);
        invertTree(root.right);

        return root;
    }

    public void swap(TreeNode node) {
        TreeNode temp = null;
        temp = node.left;
        node.left = node.right;
        node.right = temp;
    }
}