The fifteen puzzle is a type of sliding puzzle which also known as gem puzzle, boss
puzzle, mystic square, or game of fifteen. It consists of a frame of numbered square
tiles in random order with one tile missing. It normally comes in the size of 3x3 (8-
puzzle), 4x4 (15-puzzle), 5x5 (24-puzzle) and etc. The objective of this puzzle game
is to sort the tiles in correct order by making sliding moves that use the empty space.