How to calculate space inside 3 X 3 array.

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C#

CSS

I have an fixed size of rows and columns(3 X 3) table.


If user try to give input like
1 X 2
2 X 1
1 X 1
2 X 2

then my code will check how much space left inside table.

Means,
If user fills 1 X 2 means- user fill data in 1 is treated as a rowspan and 2 is treated as a colspan.
then If user enters 2 X 1 - then it should fill 2 rowsspan and 1 colspan.
It should not create new table, It should get prescribed inside 3 x 3 table.


Can anyone help me out to calculate this kind of logic

What I have tried:

I dont have any idea how to start and what should I try to calculate the things for tABLE .