wordsearch.hs

-- my friend tweeted about wordsearches and this possessed
-- me to calculate the number of possible positions for a
-- word of a given length so here we are

-- given a length l and a wordsearch of n by m characters,
-- returns the number of possible vectors that a word of
-- length l can inhabit.
v l n m
  | l <= min n m = (iw * ih * 8) + 2*(iw * s * 5) + 2*(ih * s * 5) + 4 * (s * s * 3)
  | (l > sb)
    && (l <= lb) = sb * (lb - l + 1) * 2
  | otherwise = 0
  where
    s = l - 1
    iw = n - 2*s
    ih = m - 2*s
    sb = min n m
    lb = max n m