AdventOfCode/2020/10_haskell.ipynb

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{
"cells": [
{
"cell_type": "code",
"execution_count": 1,
"metadata": {},
"outputs": [],
"source": [
"puzzle <- readFile \"10.txt\"\n",
"plines = lines puzzle"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Day 10"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Puzzle 1"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"1885"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"import Data.List (sort)\n",
"\n",
"nums = sort $ map read plines :: [Int]\n",
"\n",
"count :: Eq a => [a] -> a -> Int\n",
"count lst a = foldl (\\acc e -> if e == a then acc + 1 else acc) 0 lst\n",
"\n",
"let diffs = head nums:[(nums !! i) - (nums !! (i - 1)) | i <- [1..length nums - 1]]\n",
" in count diffs 1 * (count diffs 3 + 1)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Puzzle 2"
]
},
{
"cell_type": "code",
"execution_count": 3,
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"2024782584832"
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"import qualified Data.Map as Map\n",
"\n",
"count :: Int -> Int -> Map.Map (Int, Int) Int -> (Int, Map.Map (Int, Int) Int)\n",
"count idx joltage dp\n",
" | idx == length nums = (if joltage == last nums then 1 else 0, dp)\n",
" | nums !! idx - joltage > 3 = (0, dp)\n",
" | otherwise = case Map.lookup (idx, joltage) dp of\n",
" Just c -> (c, dp)\n",
" _ -> let\n",
" (a, dp2) = count (idx + 1) joltage dp\n",
" (b, dp3) = count (idx + 1) (nums !! idx) dp2\n",
" in (a + b, Map.union dp3 $ Map.singleton (idx, joltage) (a + b))\n",
"\n",
"fst $ count 0 0 Map.empty"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Haskell",
"language": "haskell",
"name": "haskell"
},
"language_info": {
"codemirror_mode": "Haskell",
"file_extension": ".hs",
"mimetype": "text/x-haskell",
"name": "haskell",
"pygments_lexer": "Haskell",
"version": "8.8.4"
}
},
"nbformat": 4,
"nbformat_minor": 4
}