Excluding columns already used

[thegreatgaru]

I have a list of ZIP codes a newspaper distributes to and potential markets a company may enter into. To advertise to these markets we must strategically distribute to specific ZIP codes. However, some markets overlap ZIP codes, so if multiple markets were entered into, there wouldn't be a need to buy distribution if the ZIP code is already saturated.

Below is an example table of the data:

	A	B	C	D
1		Market A	Market B	Market C
2	12345	100		100
3	12346		155
4	12347	250	250
5	12348	110		110
6	12349			500

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</tbody>

I want to have a drop down table where I would be able to select the markets. Based on how I stack them, it would give me the incremental circulation needed to cover that market. Below are 2 examples of ideal output:

Market	Additional Circulation
Market A	460
Market B	155
Market C	500

<colgroup><col><col></colgroup><tbody>
</tbody>

Market	Additional Circulation
Market B	405
Market C	710
Market A	0

<colgroup><col><col></colgroup><tbody>
</tbody>

I am looking for a formula to get the desired output for the tables.

Any help would be great!

Thanks!

 

[thegreatgaru]

Bump.