I took a pure brute force approach to this problem: Working with [x,y] coordinates is a headache. I also chose to go the route of testing every valid combination; way, way too many submissions on the Project Euler forums (and on the Internet in general) are along the lines of “I just did Ctrl+F for [...]
I started here for clarification on the problem’s requirement. I had more problem correctly parsing the input than I did in crunching the highest product (three hours versus two minutes?). :/ — using System; using System.IO; public class Eight { static void Main() { int[] a = numIn(); int b = 0; int c = [...]