二叉树的镜像

public class Solution {

    public static void MirrorBinaryTree(TreeNode root) {
        if(root == null) {
            return;
        }

        if(root.left == null && root.right == null) {
            return;
        }

        TreeNode tmp = root.left;
        root.left = root.right;
        root.right = tmp;

        if(root.left != null) {
            MirrorBinaryTree(root.left);
        }

        if(root.right != null) {
            MirrorBinaryTree(root.right);
        }
    }
}