Hello Codeforces,

I am a 56-year old life-long learner and computer-programming lover with PhD degree in Electronics and Electrical Communications Engineering from Cairo University, Egypt, and with research interest in VLSI CAD algorithms, computer architecture, digital signal and image processing. I joined Codeforces five years ago to encourage my son during his first year in college, and I participate almost regularly in long-time competitive programming challenges as time permits.

I participated last week in HackerEarth September Circuits '21 Long-Time Contest that ended yesterday, and I reached the 4th rank on the Leaderboard of the Contest. The approximate problem in the Contest was a variant to the well-known Traveling Salesman Problem (TSP). To my surprise, the first runner-up commented about four days ago that the checker program of this problem was broken and it accepted invalid solutions. As such, only two contestants managed to write wrong solutions that exploited the incorrectness of the checker in getting the highest possible score, while other contestants including me who wrote correct solutions assuming that the checker program would reject invalid solutions did not reach 1% of the score of the wrong solutions.

I am writing this blog to urge the HackerEarth team whose members announce in Codeforces invitations to regular HackerEarth Contests to review thoroughly the checker programs of the problems posted in its regular contests. The issue of broken checker took place several times in the past few months Circuits long-time Contests without any apology and without any announcement that corrective procedure would be pursued to be more sure that future contests do not include broken checker programs.

Thanks in advance for the constructive feedback and response.