Basic implementation of COUNTLESS8

countless8.py

from itertools import combinations
from functools import reduce

def countless8(a,b,c,d,e,f,g,h):
  """Extend countless5 to countless8. Same deal, except we also
    need to check for matches of length 4."""
  sections = [ a, b, c, d, e, f, g, h ]
  
  # PICKN = PICK with N arguments
  p2 = lambda q,r: q * (q == r) # PICK2
  p3 = lambda q,r,s: q * ( (q == r) & (r == s) ) # PICK3
  p4 = lambda p,q,r,s: p * ( (p == q) & (q == r) & (r == s) ) # PICK4

  lor = lambda x,y: x + (x == 0) * y # short circuiting logical or

   # important to use generator expressions here to reduce peak memory usage
  results4 = ( p4(x,y,z,w) for x,y,z,w in combinations(sections, 4) )
  results4 = reduce(lor, results4)

  results3 = ( p3(x,y,z) for x,y,z in combinations(sections, 3) )
  results3 = reduce(lor, results3)

  # We can always use our shortcut of omitting the last element
  # for N choose 2 
  results2 = ( p2(x,y) for x,y in combinations(sections[:-1], 2) )
  results2 = reduce(lor, results2)

  return reduce(lor, [ results4, results3, results2, h ])