In fact, acing the coding assignment is about coming up with a solution that uses integral maps (it is NOT to demonstrate your ability to know the language features, for me that was showing various c++ features, like lambda functions, enum class, etc) it was, did you know enough, or research enough to use integral maps, which is a O(m*n) solution. Seems relatively trivial to solve, but your ability to get hired might depend on it, so study those. Again, don't use recursion, because then they'll immediately say, well what happens when the map is 1000x1000 or just keeps getting bigger. There is no interest in your understanding of the implications of recursion, you have already failed by starting with it. Instead, build up your iterative loop, it's not hard, but your ability to get this correct immediately seems very important to how you're skills are perceived. Your ability to *eventually* get to the solution might not be sufficient, you should be able to recognize this problem, otherwise it might reflect poorly on your overall ability to develop enterprise level code.