[[[1,2,3][1,2,4],[1,2,5],[5,8]],
[[1,3][7,8],[6,1]],
[[]],
[[9,10][7,5],[6,9],[6,10]]]

OPTIMAL SOLUTION (FROM ROW #):
#1 [1,2,3]
#2 [7,8]
#3 [9,10]
Output: [[1,2,3],[7,8],[9,10]]