Topswops is a card game created by John Conway in the 1970's.



Assume you have a particular permutation of a set of   n   cards numbered   1..n   on both of their faces, for example the arrangement of four cards given by   [2, 4, 1, 3]   where the leftmost card is on top.

A round is composed of reversing the first   m   cards where   m   is the value of the topmost card.

Rounds are repeated until the topmost card is the number   1   and the number of swaps is recorded.



For our example the swaps produce:

    
    [2, 4, 1, 3]    # Initial shuffle
    [4, 2, 1, 3]
    [3, 1, 2, 4]
    [2, 1, 3, 4]
    [1, 2, 3, 4]

For a total of four swaps from the initial ordering to produce the terminating case where   1   is on top.



For a particular number    n    of cards,    topswops(n)    is the maximum swaps needed for any starting permutation of the   n   cards.



Task

The task is to generate and show here a table of    n    vs    topswops(n)    for    n    in the range   1..10   inclusive.



Note

Topswops   is also known as   Fannkuch   from the German word   Pfannkuchen   meaning   pancake.



Related tasks

   Number reversal game
   Sorting algorithms/Pancake sort


>>> from itertools import permutations
>>> def f1(p):
	i = 0
	while True:
		p0  = p[0]
		if p0 == 1: break
		p[:p0] = p[:p0][::-1]
		i  += 1
	return i
 
>>> def fannkuch(n):
	return max(f1(list(p)) for p in permutations(range(1, n+1)))
 
>>> for n in range(1, 11): print(n,fannkuch(n))
 
1 0
2 1
3 2
4 4
5 7
6 10
7 16
8 22
9 30
10 38
>>> 