Notice that the above list is a representation for a 2-dimensional crossword puzzle as shown below. Note: If both a horizontal and a vertical match is found then only select the horizontal match. For example, in the above case there is a horizontal match starting at [2,1] and there is also a vertical match starting at [1,0]. A2A. Last year begin, when I attempted CP (competitive programming), without knowing what it is on hackerrank, I failed to solve the easy problems multiple times, on multiple days, at the begin of 2015. By Rachel KleinfeldRachel Kleinfeld is a senior fellow at the Carnegie Endowment for International Peace. Her most recent book is “A Savage Order: How the World’s Deadliest Co