Thursday, June 22, 2017

Onion Omega2+ Terminal on browser

After I installed the web-based Terminal on my Omega2, I was able to login to the terminal via web-browser. Cool!


Tuesday, June 20, 2017

My Omeaga2+ OpenWRT Card

Finally, after waiting for almost 10 months, my order of Omega2+ from Onion arrived yesterday.
Will post later about the getting started experience.  For now, only pictures.



Tuesday, June 13, 2017

Interesting opinions About Job Interviews

I one day stumbled upon this site (Things I Learned From Failing Technical Interviews), a section called "Do not be Yourself" intrigued me.

Contrary to the popular suggestions from many career advisers to be yourself during job interview, the person suggests the interviewee not to be him/herself, but to be a robot.  I totally agree with his opinion.  If you've done multiple job interviews for software engineer job position, you might have experience unease when the interviewer expect you to be perfect in coding in front of him/her. No syntax errors, have to memorize the APIs, etc.  The blogger continues to say that hiring a candidate is just like another upgrade of server or adding another PC in the server cluster, which is to offload work from the team to the new hired.

It is almost a guarantee that you will be asked something you don't know and even an hour of thinking about it and problem solving around it you still won't know.  Sometimes you get asked something you've known it long time ago, but can no longer able to grasp it and explain it to them.  You feel like you're an idiot with glamorous title and said experiences (and preconceive that the interviewer must says in his mind, "why the heck this guy is applying for this position"?)

Another jobseeking-related blog: I will get That Job at Google

Wednesday, June 7, 2017

Swamping two variables without temporary variable

Based on the Boolean Algebra, where XOR operator is commutative and associative:

A = A ⊕ B
B = B ⊕ A = B ⊕ (A ⊕ B) = B ⊕ (B ⊕ A) = (B ⊕ B) ⊕ A
  = 0 ⊕ A = A
A = A ⊕ B = (A ⊕ B) ⊕ A = B ⊕ (A ⊕ A) = B

So the steps are:

A = A^B;
B = B^A;
A = A^B;

Another way is by doing arithmetics:

A = A - B;
B = A + B;
A = B - A;

Or
A = A + B;
B = A - B;

A = A - B;

If we look at carefully, the XOR operator is actually a half-adder operation (with carry bit).

A ⊕ B = A' * B + A * B', where if A=1 the result would be equal to B', else equal to B.