[nangtrongvuon]

I'm Vietnamese too and what he (the author) wrote here in this blog post seems very much the exception rather than the norm.

He most likely visited an Olympiad team, where they solve problems like these to compete. Most other schools, such as the ones I went to, had IT/CS as a side class (meaning they don't get that much attention from both students and teachers alike) rather than a main class (think Math, English, Vietnamese etc).