2023/day04.m4

   1 divert(-1)dnl -*- m4 -*-
   2 # Usage: m4 [-Dfile=day04.input] day04.m4
   3
   4 include(`common.m4')ifelse(common(04), `ok', `',
   5 `errprint(`Missing common initialization
   6 ')m4exit(1)')
   7
   8 define(`do', `ifelse($1, |, , `+(len($1)*index(`$*,', `,$1,')>0)$0(
   9   shift($@))')')
  10 define(`bump', `define(`$1', eval(defn(`$1')+$2))')
  11 define(`_C', `bump(`part1', `(1<<$1)/2')bump(`part2', `$3')forloop($2,
  12   eval($1+$2), `bump(`S'', `, $3)')')
  13 define(`C', `ifelse($1,,`C(shift($@))',`_C(eval(do(shift($@))),$1,incr(
  14   0defn(`S$1')))')')
  15 translit(include(defn(`file')), `a 'nl`:rd', `(,)')
  16
  17 divert`'part1
  18 part2