Paste: aoc2025d5

use-modules
  : ice-9 pretty-print
    . #:select
    : pretty-print . pp
  ice-9 rdelim
  srfi srfi-1
  srfi srfi-26
  srfi srfi-197

define : pipe . fs
  cond
    : null? fs
      lambda args : apply values args
    : null? : cdr fs
      car fs
    else
      lambda args
        fold
          lambda (f acc) (f acc)
          apply (car fs) args
          cdr fs

define : string-paras input
  define : combine line acc
    let
      : new? : car acc
        paras : cdr acc
      if : string-null? line
        cons #t paras
        if : or new? : null? paras
          cons #f : cons (list line) paras
          cons #f : cons (cons line (car paras)) (cdr paras)

  chain
    string-split input #\newline
    fold combine (cons #t '()) _
    cdr _
    filter (compose not null?) _
    map reverse _
    reverse _

define : prep input
  define : list->pair xs
    cons (car xs) (cadr xs)

  define : go db
    let
      : ranges : car db
        ids : map string->number : cdr db
      chain
        . ranges
        map
          pipe
            cut string-split <> #\-
            cut map string->number <>
            . list->pair
          . _
        cons _ ids

  chain
    string-paras input
    list->pair _
    go _

define : merge ranges
  define : cmp p r
    let
      : pl : car p
        pr : cdr p
        rl : car r
        rr : cdr r
      cond
        : = pl rl
          < pr rr
        else : < pl rl

  define : combine range stack
    if : null? stack
      cons range stack
      let*
        : l : car range
          r : cdr range
          prev : car stack
          prevl : car prev
          prevr : cdr prev
        if : < (+ prevr 1) l
          cons range stack
          cons (cons prevl (max prevr r)) (cdr stack)

  chain
    sort ranges cmp
    fold combine '() _
    reverse _

define : all-fresh-ids ranges
  define : width range
    chain (- (cdr range) (car range)) (+ 1 _)

  chain
    map width ranges
    apply + _

define : main args
  let*
    : db : prep : read-delimited ""
      ranges : car db
      ids : cdr db
    pp : all-fresh-ids : merge ranges

main : command-line