The square tiling problem

 The square tiling problem is about how to cover a square with square tiles of given sizes.

 For a square of size 19 and tiles of sizes [10,9,7,6,4,4,3,3,3,3,3,2,2,2,1,1,1,1,1,1] one of the answers is

 Xs = [1, 1, 10, 11, 11, 15, 17, 17, 17, 17, 17, 10, 12, 14, 16, 16, 19, 19, 19, ...]
Ys = [1, 11, 11, 1, 7, 7, 1, 4, 11, 14, 17, 18, 18, 18, 18, 19, 7, 8, 9, ...]

How i should interpret this result? I imagine X,Y are coordinates and i plote them but couldn't find a pattern.

Thank's,

 Christian