regnault.dev
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day 1
+2
src/aoc.gleam
+2
src/aoc.gleam
···
1
1
import birl
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2
import birl/duration
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+
import days/day1
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import gleam/erlang
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import gleam/int
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import gleam/io
···
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let start = birl.now()
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case day {
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0 -> io.println_error("Invalid day")
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+
1 -> day1.start()
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_ -> io.println("Tried to run day " <> int.to_string(day))
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}
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birl.now()
+124
src/days/day1.gleam
+124
src/days/day1.gleam
···
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+
import gleam/dynamic
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+
import gleam/float
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+
import gleam/int
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+
import gleam/io
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+
import gleam/list
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+
import gleam/result
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+
import gleam/string
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import simplifile
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+
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type Direction {
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Left
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Right
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}
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+
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type Action {
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Action(Direction, Int)
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}
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+
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pub fn start() -> Nil {
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let assert Ok(content) = simplifile.read("inputs/day1.txt")
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let data = parse(content)
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+
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let _ = io.debug(part1(data))
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let _ = io.debug(part2(data))
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+
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Nil
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}
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+
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fn parse(data: String) {
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data
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|> string.split("\n")
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|> list.map(fn(l) {
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let chars =
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l
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|> string.to_graphemes()
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+
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let direction_string =
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chars
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|> list.first
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|> result.unwrap("")
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+
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let direction = case direction_string {
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"L" -> Left
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"R" -> Right
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_ -> Left
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}
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+
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let number =
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chars
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|> list.drop(1)
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|> string.join("")
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|> int.parse
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|> result.unwrap(0)
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+
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Action(direction, number)
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})
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}
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+
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fn part1(data: List(Action)) {
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data
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|> list.fold([50], fn(acc: List(Int), elem: Action) {
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let current =
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acc
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|> list.first
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|> result.unwrap(0)
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+
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let new = case elem {
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Action(Left, x) -> { current - x } % 100
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Action(Right, x) -> { current + x } % 100
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}
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+
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let new = case new < 0 {
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True -> new + 100
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False -> new
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}
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+
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acc
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|> list.prepend(new)
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})
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|> list.count(fn(x) { x == 0 })
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}
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+
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fn part2(data: List(Action)) {
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data
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|> list.fold([#(50, 0)], fn(acc: List(#(Int, Int)), elem: Action) {
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let #(current, _) =
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acc
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|> list.first
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|> result.unwrap(#(0, 0))
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+
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let Action(dir, clicks) = elem
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+
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let remaining = clicks % 100
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+
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let reached_zero = case dir {
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Left -> current - remaining <= 0 && current != 0
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Right -> current + remaining >= 100 && current != 0
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}
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+
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let reached =
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{ clicks / 100 }
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+ case reached_zero {
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True -> 1
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False -> 0
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}
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+
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let new = case elem {
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Action(Left, x) -> { current - x } % 100
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Action(Right, x) -> { current + x } % 100
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}
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+
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let new = case new < 0 {
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True -> new + 100
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False -> new
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}
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+
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acc
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|> list.prepend(#(new, reached))
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})
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|> list.fold(0, fn(acc, x) {
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let #(_, cnt) = x
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acc + cnt
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})
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+
}