剑指offer_58

public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;
    public TreeNode(int val) {
        this.val = val;
    }
}
*/
public class  {
    boolean isSymmetricalHelper(TreeNode left, TreeNode right){
        if(left == null && right == null){
            return true;
        }
        if((left == null && right != null) || (left != null && right == null)){
            return false;
        }
        if(left.val != right.val){
            return false;
        }
        
        return isSymmetricalHelper(left.left, right.right) && isSymmetricalHelper(left.right, right.left);
        
    }
    
    boolean isSymmetrical(TreeNode pRoot)
    {
        if(pRoot == null){
            return true;
        }
        return isSymmetricalHelper(pRoot.left, pRoot.right);
    }
}