In the example I am giving below, I would like the result in Column G to be what is in Column C, unless it already exists in Column G in rows above it:
These rows represent students' choices for topics (C is their 1st choice, D is their 2nd choice, etc.) and each topic needs to be unique. The first student gets their first choice, and then no one else can choose it. If another student in a successive row has chosen that as their first choice, then that student will have to be assigned their 2nd choice from Column D instead.
I have contemplated somehow using VLOOKUP or FILTER or even IF statements, but with 250 students/rows, that could get cumbersome.
What is the best way to go about this?