comparing the contents of two huge text files quickly

Question

what i\'m basically trying to do is compare two HUGE text files and if they match write out a string, i have this written but it\'s extremely slow. I was hoping you guys might

Answer 1

You have a cartesian product, so it makes sense to index one side instead of doing an enhaustive linear search.

Extract the keys from one file and use either a Set or SortedList data structure to hold them. This will make the lookups much much faster. (Your overall algorithm will be O(N lg N) instead of O(N**2) )