Tableau possible IF LOD calculation - if-statement

Question

This one seems simple but I'm stumped. Hoping someone has come across this one before.
I want to show:
State Category Sales$ if Furniture is the highest Sales$ category for that State
Ex: Arizona Furniture $13,525
However, if Furniture is not the top Sales $ Category I want to show 0 or NULL or "Red Flag". Any could work,"Red Flag" would be best but I'm not sure we can couple an 'ag' with a string.
Ex: Alabama Furniture "Red Flag"
Thanks for any suggestions that get this right!
State Category Sales
Alabama Furniture $6,332
Office Supplies $4,209
Technology $8,969
Arizona Furniture $13,525
Office Supplies $10,006
Technology $11,751
Arkansas Furniture $3,188
Office Supplies $4,565
Technology $3,925
California Furniture $156,065
Office Supplies $142,352
Technology $159,271
Colorado Furniture $13,243
Office Supplies $7,899
Technology $10,966

Answer 1

Let's go part by part. First let's create a [max_sales] field:
{ FIXED [State] : MAX([Sales]) }
This will give you the max sales of each state, among the categories. I'm assuming that's the lowest level of detail (category). If it is not, you can use another LOD calculation to have the figures for each category:
{ FIXED [Category] : SUM([Sales]) }
And use this field on the first calculation.
Now for the next part. You can't mix integers with strings, but you can always convert int to str. I would do:
IF [Category] = 'Furniture'
THEN IF [Sales] < [max_sales]
THEN 'Red Flag'
ELSE STR([Sales])
END
ELSE #I have no idea what you want here
END
Again, if category is no the lowest level of detail, use SUM([Sales]) instead of just sales (and MAX([max_sales]) if Tableau says you can't mix aggregated with non-aggregated fields)