2023/day06.m4

   1 divert(-1)dnl -*- m4 -*-
   2 # Usage: m4 [-Dfile=day06.input] day06.m4
   3
   4 include(`common.m4')ifelse(common(06), `ok', `',
   5 `errprint(`Missing common initialization
   6 ')m4exit(1)')
   7
   8 include(`math64.m4')
   9 define(`input', translit(include(defn(`file')), Tsemantic))
  10 define(`half', `_$0(mul(5, $1))')define(`_half', `substr($1, 0, decr(len($1)))')
  11 define(`_search', `ifelse(, $@, lt64(mul64($4, eval($1 - $4)), $2), 0,
  12   `search($1, $2, $3, $4)', `search($1, $2, $4, $5)')')
  13 define(`search', `_$0($1, $2, $3, half(add($3, $4)), $4)')
  14 define(`count', `eval($1-search($1, $2, 0, half($1))*2+1)')
  15 define(`zip', `ifelse($1$2, ()(), , first$1,, `zip((shift$1),$2)', first$2,,
  16   `zip($1,(shift$2))', `,count(first$1, first$2)zip((shift$1),(shift$2))')')
  17 define(`part1', mul(1zip(translit(input, :D nl, (,,)))))
  18 define(`part2', count(translit(input, nl :D, `,')))
  19
  20 divert`'part1
  21 part2