{
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   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "vscode": {
     "languageId": "racket"
    }
   },
   "outputs": [],
   "source": [
    "#lang iracket/lang #:require racket\n",
    "(require advent-of-code\n",
    "         threading\n",
    "         rebellion/collection/entry\n",
    "         rebellion/collection/multidict)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "vscode": {
     "languageId": "racket"
    }
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<code>'(acc . 49)</code>"
      ],
      "text/plain": [
       "'(acc . 49)"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(define raw-instructions (~> (fetch-aoc-input (find-session) 2020 8) (string-split \"\\n\")))\n",
    "\n",
    "(define instruction-set (for/hash ([instruction (in-list raw-instructions)] [i (in-naturals)])\n",
    "  (match-define (list op val) (string-split instruction))\n",
    "  (values i (cons (string->symbol op) (string->number val)))))\n",
    "\n",
    "(hash-ref instruction-set 0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "vscode": {
     "languageId": "racket"
    }
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<code>1949</code>"
      ],
      "text/plain": [
       "1949"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(define (execute [instruction (hash-ref instruction-set 0)] [acc 0] [line 0] [visited (set)])\n",
    "  (match instruction\n",
    "    [_\n",
    "     #:when (set-member? visited line)\n",
    "     acc]\n",
    "    [(cons 'acc n)\n",
    "     (define new-line (add1 line))\n",
    "     (execute (hash-ref instruction-set new-line) (+ acc n) new-line (set-add visited line))]\n",
    "    [(cons 'jmp n)\n",
    "     (define new-line (+ n line))\n",
    "     (execute (hash-ref instruction-set new-line) acc new-line (set-add visited line))]\n",
    "    [(cons 'nop _)\n",
    "     (define new-line (add1 line))\n",
    "     (execute (hash-ref instruction-set new-line) acc new-line (set-add visited line))]))\n",
    "\n",
    "(execute)\n"
   ]
  }
 ],
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   "display_name": "Racket (trusted)",
   "language": "racket",
   "name": "racket-trusted"
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  "language_info": {
   "codemirror_mode": "scheme",
   "file_extension": ".rkt",
   "mimetype": "text/x-racket",
   "name": "Racket",
   "pygments_lexer": "racket",
   "version": "8.7"
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