Excel 2007 use array formula to flag conditional data

Hey All,

Here's my problem:

I need to "Flag" each of the rows above that meet the following conditions:

ALL PARTs that have a CATEGORY of "B", but not "A", keeping in mind that there are duplicate parts within the list. Here's an example:

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So, the output of the data above would yield:

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I had an array formula working earlier using a SUM and IF statement within an array formula but can't seem to replicate it. I attached the data as reference.

Can anyone help me create the formula to "Flag" the above rows if the conditions are met?




thanks