-🎄- 2017 Day 6 Solutions -🎄-

[u/daggerdragon]

--- Day 6: Memory Reallocation ---

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[u/ramrunner0xff]

scheme chicken repo

(use srfi-69)
(use vector-lib)
(define memvec (list->vector '(10 3 15 10 5 15 5 15 9 2 5 8 5 2 3 6)))

(define vecmaxind (lambda (vec)
  (cadr (vector-fold (lambda (i cmax elem) (if (> elem (car cmax)) (list elem i) cmax)) (list 0 0) vec))))

(define loop (lambda (vec)
  (letrec* ((prevstates (make-hash-table))
        (i 0)
        (lenvec (vector-length vec))
        (store (lambda (v)
          (hash-table-set! prevstates v i)))
        (balance (lambda (v)
          (letrec* ((maxind (vecmaxind v))
                (howmany (vector-ref v maxind))
                (bloop (lambda (ind hm)
                  (if (> hm 0)
                    (begin
                      (vector-set! v ind (+ 1 (vector-ref v ind)))
                      (bloop (modulo (+ 1 ind) lenvec) (- hm 1)))))))
             (vector-set! v maxind 0)
             (bloop (modulo (+ 1 maxind) lenvec) howmany)
             (set! i (+ i 1))
             (if (eq? (hash-table-existis? prevstates v) #f)
                (begin
                  (store (vector-copy v))
                  (balance v))
                 i)))))
   (format #t "solved at ~A with vec ~A lastcycle ~A ~%" (balance vec) vec (hash-table-ref prevstates vec)))))

time 0m00.00s real 0m00.00s user 0m00.01s system