public boolean isSymmetricTree(TreeNode root){

if(root == null)

return false;

else

return isSample(root.getLeft(), root.getRight());

}

private boolean isSample(TreeNode left, TreeNode right){

if(left == null && right == null)

return true;

else if(left == null || right == null)

return false;

else

return left.getVal() == right.getVal() && isSample(left.getLeft(), right.getRight()) && isSample(left.getRight(), right.getLeft());

}

public static void main(String[] args) {

// TODO Auto-generated method stub

}