The 2nd part of the interview session was about 1 coding challenge. So the scenario was that given a square NxN matrix where N is an arbitrary positive integer, the elements represent the vaccination status on an imaginary city. So they are visualized to be located in a squarish manner. There are 3 statuses, namely, 0 represents unvaccinated, 1 represents vaccinated, 2 represents infected. If a person with status 0 is adjacent to at least 1 person with status 2 in his/her 4 cardinal points (up, down, left, right), then he/she will get infected. Person with status 2 at diagonal direction won't be able to infect other person. If person with status 0 is surrounded by people with status 1 at his/her 4 cardinal points, he/she won't get infected. Given this scenario, the question is to determine how many times does propagation of infection should happen so that all unvaccinated people in the NxN matrix are infected. Here, 1 infection propagation means refers to people with status 0 getting infected with people with status 2 for being directly adjacent to them. Other people with status 0 who are adjacent to the newly infected people will only be infected in the next infection propagation.
