! Basically, ! 1) reject all invalid tickets. ! 2) flip the tickets so we're looking at columns of all tickets instead of individual tickets. ! 3) map ALL valid fields to each column index. ! 4) this leaves you with a smooth progression of field counts from 1 to 20. ! 5) the only field index we know for sure is the one with only a single field. Add it to a new assoc, then delete that entry from EVERY entry in the original mapping. ! 6) This will leave you with a new index that has only one field. Repeat this process until the original mapping is empty. ! 7) Now that we have the final field/index pairs in the new assoc, use it to index your ticket and solve the problem.