二叉树的对称和镜像问题

这道题其实就是验证二叉树是否为镜像二叉树
一层一层递归判断：

public class Solution {
    boolean isSymmetrical(TreeNode pRoot)
    {
        return pRoot == null || judge(pRoot.left, pRoot.right);
    }

    public boolean judge(TreeNode left, TreeNode right){
        if(left == null && right == null)
            return true;
        else if(left == null || right == null)
            return false;

        if(left.val != right.val)
            return false;
        else 
            return judge(left.left, right.right) && judge(left.right, right.left);
    }
}

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

}