Please explain

Apply the Kahn's algorithm to solve the topological sorting problem for the following digraph. Present the topological order as you learned in the class. For the problem, you don't need to present the "in-degree" array. Just present the topological order. Also, you have to follow our convention of alphabetical order. [Puzzle] Refer to the puzzle named "A King's Reach" covered in the "week_5_4" file. In the puzzle, we assumed that a king piece can move to a horizontally, vertically, or diagonally adjacent square. Then, we identified how many different squares the king can stay after n moves. For this quiz, assume that a king piece can move to a horizontally or vertically adjacent square. It can't move to a diagonally adjacent square. Write your answers clearly for the following four questions. (a) For n is 1 , a king can stay different squares. (b) For n is 2, a king can stay different squares. (c) For n is 3 , a king can stay different squares. (d) Based on the answers above, present a formula for the general number n