2017/day20.m4

   1 divert(-1)dnl -*- m4 -*-
   2 # Usage: m4 [-Dhashsize=H] [-Dfile=day20.input] day20.m4
   3 # Optionally use -Dverbose=1 to see some progress
   4
   5 include(`common.m4')ifelse(common(20, 65537), `ok', `',
   6 `errprint(`Missing common initialization
   7 ')m4exit(1)')
   8
   9 define(`D', defn(`define'))define(`E', defn(`eval'))
  10 define(`cnt', 0)define(`best', 9999999)
  11 define(`abs', ``$1*(1-2*($1<0))'')
  12 define(`d', `E(abs($1)+abs($2)+abs($3))')
  13 define(`P', `D(`p'cnt, `$@')')
  14 define(`V', `D(`v'cnt, `$@')')
  15 define(`A', `D(`a'cnt, `$@')_$0(d($@))D(`cnt', incr(cnt))')
  16 define(`_A', `ifelse($1, best, `pushdef(`group', cnt)', E($1 < best), 1,
  17   `undefine(`group')D(`group', cnt)D(`best', $1)')')
  18 translit((include(defn(`file'))), `<>pva=', `()PVA')
  19
  20 define(`push', `pushdef(`p$1', defn(`p$1'))pushdef(`v$1',
  21   defn(`v$1'))pushdef(`a$1', defn(`a$1'))')
  22 define(`pop', `popdef(`p$1')popdef(`v$1')popdef(`a$1')')
  23 define(`b', `D(`$1',E(`$2+$5')`,'E(`$3+$6')`,'E(`$4+$7'))')
  24 define(`adj', `b(`v$1',v$1,a$1)b(`p$1',p$1,v$1)')
  25 define(`settle', `stack_foreach(`group', `_$0')ifdef(`S', `popdef(`S')$0()')')
  26 define(`_settle', `ifdef(`d$1',,`ifelse(check(d(p$1),d(v$1),adj($@)d(p$1),
  27   d(v$1)),1,`D(`S')')')')
  28 define(`check', `E(`$1>$3||$2>$4')')
  29 define(`find', `define(`best', 9999999)stack_foreach(`group', `_$0')')
  30 define(`_find', `ifelse(eval(d(v$1) < best), 1, `define(`part1', $1)define(
  31   `best', d(v$1))')')
  32 stack_foreach(`group', `push')
  33 define(`stable', 0)
  34 settle()
  35 find()
  36 stack_foreach(`group', `pop')
  37
  38 define(`part2', cnt)
  39 define(`drop', `define(`part2', decr(part2))')
  40 define(`n', `translit(``$1_$2_$3'', `-', `_')')
  41 define(`adj', `$0_1($2`_'n(p$1))b(`v$1',v$1,a$1)b(`p$1',p$1,v$1)$0_2(
  42   $3`_'n(p$1),$1)')
  43 define(`adj_1', `popdef(`P$1')')
  44 define(`adj_2', `ifdef(`P$1',`_$0(`$1')D(`d$2')drop()',`D(`P$1',$2)')')
  45 define(`_adj_2', `ifelse(P$1,,,`drop()D(`d'P$1)D(`P$1')')')
  46 define(`settle', `output(1, `...$1 'part2)forloop(0, 'decr(cnt)`, `_$0(',
  47   `, $1, $2)')ifdef(`S', `popdef(`S')$0($2, incr($2))')')
  48 settle(0, 1)
  49
  50 divert`'part1
  51 part2