剑指offer（18）二叉树镜像

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public void Mirror(TreeNode root) {
        if(root == null){return;}
        if(root.left == null && root.right == null){return;}
        TreeNode node = root.left;
        root.left = root.right;
        root.right = node;
        if(root.left!=null){Mirror(root.left);}
        if(root.right!=null){Mirror(root.right);}
        
    }
}