day 15 with extra hash powers

md515.cr

require "crypto/md5"

hash = "0" * 32
zeroes = Array.new(32, 1)

ROWS = 8
almost = 0
hashes = Array.new(ROWS, "")
hashes[0] = hash

(1..(1.0 / 0.0)).each { |t|
  hash = Crypto::MD5.hex_digest(hash)
  hashes[t % ROWS] = hash
  hash.each_char.with_index { |c, i|
    if c == '0'
      zeroes[i] += 1
      if zeroes[i] == ROWS
        hit_time = t - ROWS
        puts "HIT at t=#{hit_time} at column #{i}"
        puts "t=#{hit_time} #{" " * i}*"
        (1..ROWS).each { |dt|
          row_time = hit_time + dt
          puts "t=#{row_time} #{hashes[row_time % ROWS]}"
        }
        puts "We came close #{almost} times!"
        exit 0
      end
    else
      if zeroes[i] == ROWS - 1
        puts "So close! at #{t}"
        almost += 1
      end
      zeroes[i] = 0
    end
  }
}

output.txt

So close! at 4445623
So close! at 12122100
So close! at 16570529
So close! at 27420196
So close! at 34458826
So close! at 36400105
So close! at 38363659
So close! at 79147987
So close! at 91223760
So close! at 100304390
So close! at 107333146
So close! at 107567039
So close! at 112950979
So close! at 120967557
So close! at 127208246
So close! at 139247969
So close! at 158260385
So close! at 164031321
So close! at 181484528
So close! at 183846084
So close! at 191529496
So close! at 203156255
So close! at 203932778
HIT at t=204947638 at column 13
t=204947638              *
t=204947639 f1773abd2e79f01510f9c2a2b4336136
t=204947640 2a13793c429cd0fe9f803d12341f9dfd
t=204947641 4a48eedba347e0fba6a4b6d5d977736c
t=204947642 01e4ca27df8a3059ce2377cb81ed7ea8
t=204947643 e43d5eca6331d0b88dabb8c20aa47106
t=204947644 47462d6606bd20a74d97a1e7aea23070
t=204947645 12116b454ccd8049a4dc2cd882bd9f3f
t=204947646 0132b44673c240e3d51e0cde2bcd2921
We came close 23 times!