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234 lines
6.6 KiB
234 lines
6.6 KiB
#!/usr/bin/guile -s
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!#
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;=============== functions with side effects (I/O) ======================
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(use-modules (ice-9 rdelim))
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(define (read-lines)
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((lambda (line)
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(if (eof-object? line) '() (cons line (read-lines))))
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(read-line)))
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(define (display-ln value) (list (display value) (display "\n")))
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(define (assert-eq error-message expected actual)
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(if (not (equal? expected actual))
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(display-ln (list error-message (list "expected" expected) (list "actual" actual)))
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'()))
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(define (tee value) (car (list value (display-ln value))))
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;=============== end of functions with side effects ======================
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(define (id value) value)
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(define (is-not value) (lambda (x) (not (equal? x value))))
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(define (is-not-empty value) (not (null? value)))
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(define (prepend first-value) (lambda (rest) (cons first-value rest)))
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;=============== combinators ======================
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(define (Y f) (f (lambda (x) ((Y f) x))))
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(define (Y2 f) (f (lambda (x y) ((Y2 f) x y))))
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(assert-eq "Y test 1 (factorial) failed"
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120
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((Y (lambda (f) (lambda (n) (if (= n 0) 1 (* n (f (- n 1))))))) 5))
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(assert-eq "Y2 test 1 (pascal triangle) failed"
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35
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((Y2 (lambda (f) (lambda (a b)
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(if (= a 0) 1 (if (= b 0) 1 (+ (f (- a 1) b) (f a (- b 1))))))))
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3 4))
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(define (reduce-right initial reducer) (Y
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(lambda (f) (lambda (values)
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(if (null? values) initial (reducer (car values) (f (cdr values))))))))
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(define (map mapper) (reduce-right '()
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(lambda (current accumulator) (cons (mapper current) accumulator))))
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(define (concat left right)
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((reduce-right right (lambda (current accumulator) (cons current accumulator)))
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left))
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;=============== flat ======================
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(define flat (reduce-right '() concat))
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(assert-eq "flat test 1 failed"
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'(1 2 3 4 5 (6 7) 8)
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(flat '((1 2) (3 4) (5 (6 7) 8))))
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(define (filter predicate) (reduce-right '()
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(lambda (current accumulator)
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(if (predicate current) (cons current accumulator) accumulator))))
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;=============== first ======================
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(define (first predicate) (reduce-right '()
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(lambda (current accumulator)
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(if (predicate current) current accumulator))))
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(assert-eq "first with is-not-empty test 1 failed"
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'(1 2 3)
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((first is-not-empty) '(() (1 2 3))))
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(define (coalesce-not-empty default-lazy) (lambda (value) (if (null? value) (default-lazy) value)))
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(define (truthy-chaining f) (lambda (value) (if value (f value) #f)))
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(define (compose-two f g) (lambda (x) (f (g x))))
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(define compose (reduce-right id compose-two))
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(define (combine combiner)
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(lambda (a b) (if (null? a) b (if (null? b) a (combiner a b)))))
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(define sum (reduce-right 0 +))
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(define (repeat value) (Y
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(lambda (f) (lambda (n)
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(if (= n 0) '() (cons value (f (- n 1))))))))
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;=============== starts-with ======================
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(define starts-with (Y2
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(lambda (f) (lambda (prefix values)
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(if
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(null? prefix)
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values
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(if
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(null? values)
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#f
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(if (equal? (car prefix) (car values))
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(f (cdr prefix) (cdr values))
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#f)))))))
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(assert-eq "starts-with test 1 failed"
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'(4)
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(starts-with '(1 2 3) '(1 2 3 4)))
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(assert-eq "starts-with test 2 failed"
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'()
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(starts-with '(1 2 3) '(1 2 3)))
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(assert-eq "starts-with test 3 failed"
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#f
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(starts-with '(1 2 3) '(1 2)))
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(assert-eq "starts-with test 4 failed"
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#f
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(starts-with '(1 2 3) '(4 5 6 7)))
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(assert-eq "starts-with test 5 failed"
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(string->list "de")
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(starts-with (string->list "abc") (string->list "abcde")))
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;=============== tokenize ======================
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(define (tokenize-generic tokens next) (Y
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(lambda (f) (lambda (values)
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(if
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(null? values)
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'(())
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((compose (list
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(coalesce-not-empty (lambda () (f (cdr values))))
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flat
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(filter id)
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(map
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(lambda (token)
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((truthy-chaining (compose (list
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(map (prepend (car token)))
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(lambda (rest) (f (next rest values))))))
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(starts-with (cdr token) values))))))
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tokens))))))
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(define (tokenize tokens)
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(tokenize-generic tokens (lambda (rest values) rest)))
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(assert-eq "tokenize test 1 failed"
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'((101 201) (101 202) (102 201) (102 202))
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((tokenize '((101 1) (102 1) (201 2) (202 2)))
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'(1 2)))
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(assert-eq "tokenize test 2 failed"
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'((101 102 102 101 102))
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((tokenize '((101 1) (102 2)))
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'(1 2 3 2 1 2)))
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(assert-eq "tokenize test 3 failed"
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'((101 102 101) (101 1021) (1012 101))
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((tokenize '((101 1) (102 2) (1012 1 2) (1021 2 1)))
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'(1 2 1)))
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(define (tokenize-aoc tokens)
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(tokenize-generic tokens (lambda (rest values) (cdr values))))
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;=============== solution ======================
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(define solution-tokens
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(list
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(cons #\0 (string->list "0"))
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(cons #\1 (string->list "1"))
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(cons #\2 (string->list "2"))
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(cons #\3 (string->list "3"))
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(cons #\4 (string->list "4"))
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(cons #\5 (string->list "5"))
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(cons #\6 (string->list "6"))
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(cons #\7 (string->list "7"))
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(cons #\8 (string->list "8"))
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(cons #\9 (string->list "9"))
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(cons #\1 (string->list "one"))
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(cons #\2 (string->list "two"))
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(cons #\3 (string->list "three"))
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(cons #\4 (string->list "four"))
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(cons #\5 (string->list "five"))
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(cons #\6 (string->list "six"))
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(cons #\7 (string->list "seven"))
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(cons #\8 (string->list "eight"))
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(cons #\9 (string->list "nine"))))
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(assert-eq "solution tokenize test 1 failed"
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(list (string->list "219"))
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((tokenize-aoc solution-tokens)
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(string->list "two1nine")))
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(assert-eq "solution tokenize test 2 failed"
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(list (string->list "823"))
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((tokenize-aoc solution-tokens)
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(string->list "eightwothree")))
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(assert-eq "solution tokenize test 3 failed"
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(list (string->list "123"))
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((tokenize-aoc solution-tokens)
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(string->list "abcone2threexyz")))
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(assert-eq "solution tokenize test 4 failed"
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(list (string->list "2134"))
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((tokenize-aoc solution-tokens)
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(string->list "xtwone3four")))
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(assert-eq "solution tokenize test 5 failed"
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(list (string->list "49872"))
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((tokenize-aoc solution-tokens)
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(string->list "4nineeightseven2")))
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(assert-eq "solution tokenize test 6 failed"
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(list (string->list "18234"))
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((tokenize-aoc solution-tokens)
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(string->list "zoneight234")))
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(assert-eq "solution tokenize test 7 failed"
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(list (string->list "76"))
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((tokenize-aoc solution-tokens)
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(string->list "7pqrstsixteen")))
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(define solve-line (compose (list
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string->number
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list->string
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(reduce-right '()
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(combine (lambda (left right) (cons (car left) (cdr right)))))
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(map (lambda (char) ((repeat char) 2)))
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car
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(tokenize-aoc solution-tokens)
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string->list)))
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(define solve-all (compose (list
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sum
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(map solve-line))))
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(display (solve-all (read-lines)))
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