面试题：对称二叉树

//二叉树一般用到递归
public class Solution {
    boolean isSymmetrical(TreeNode pRoot){
        if(pRoot==null) return true;
        return isSymmetrical(pRoot.left,pRoot.right);
    }
    boolean isSymmetrical(TreeNode left,TreeNode right){
        if(left==null&&right==null) return true;
        if(left==null||right==null) return false;
        if(left.val==right.val){
            return isSymmetrical(left.left,right.right)&&isSymmetrical(left.right,right.left);
        }
        return false;
    }
}