对称的二叉树

public class Solution {
    boolean isSymmetrical(TreeNode pRoot)
    {
        if(pRoot == null) return true;
        return isSame(pRoot.left,pRoot.right);
        
    }
    public boolean isSame(TreeNode pRoot1,TreeNode pRoot2){
        if(pRoot1==null && pRoot2!=null) return false;
        if(pRoot1!=null && pRoot2 == null) return false;
        if(pRoot1 == null && pRoot2 == null) return true;
        if(pRoot1.val != pRoot2.val) return false;
        return isSame(pRoot1.left,pRoot2.right)&&isSame(pRoot1.right,pRoot2.left);
    }
}