Question

Im wondering how could i find if 2 square share a same side.

i have 2 information:
position and size

position is the left up corner of the square

+---+---+   
|   s   |   
|   s   |   
+---+---+

here s is the shared side of both square

Answer 1

Since you lack “orientation” as a datum, we will assume that they are orthogonal to the axes. At this point it becomes a matter of checking if either of the horizontal or vertical edges are collinear (which is trivial since you don’t need to worry about orientation), and then seeing if either corner falls within the other square’s side or vice versa.