regnault.dev
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Day 3
+2
src/aoc.gleam
+2
src/aoc.gleam
···
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2
import birl/duration
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import days/day1
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import days/day2
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+
import days/day3
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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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0 -> io.println_error("Invalid day")
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1 -> day1.start()
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2 -> day2.start()
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3 -> day3.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()
+74
src/days/day3.gleam
+74
src/days/day3.gleam
···
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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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import utils/utils
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pub fn start() -> Nil {
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let assert Ok(content) = simplifile.read("inputs/day3.txt")
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let data = parse(content)
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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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string.split(data, "\n")
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|> list.map(string.to_graphemes)
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|> list.map(list.map(_, int.parse))
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|> list.map(list.map(_, result.unwrap(_, 0)))
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}
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+
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type LstMaxIdx {
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LstMaxIdx(idx: Int, value: Int)
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}
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+
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fn max_int_from_index(lst: List(Int), start_from: Int, last_offset: Int) {
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lst
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|> list.drop(start_from)
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|> list.index_fold(LstMaxIdx(0, 0), fn(max, num, idx) {
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case idx >= { list.length(lst) - start_from - last_offset } {
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True -> max
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False ->
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case max.value < num {
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True -> LstMaxIdx(idx + start_from, num)
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False -> max
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}
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}
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})
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}
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+
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fn part1(data: List(List(Int))) {
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list.map(data, fn(x) {
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let first = max_int_from_index(x, 0, 1)
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let second = max_int_from_index(x, first.idx + 1, 0)
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first.value * 10 + second.value
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})
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|> list.fold(0, int.add)
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}
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+
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fn part2(data: List(List(Int))) {
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let range = utils.create_int_range(0, 12)
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list.map(data, fn(x) {
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list.fold(range, #(0, 0), fn(acc, offset) {
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let res = max_int_from_index(x, acc.1, { 11 - offset })
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#(
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acc.0
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+ res.value
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* {
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int.power(10, float.subtract({ 12.0 -. 1.0 }, int.to_float(offset)))
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|> result.unwrap(0.0)
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|> float.round
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},
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res.idx + 1,
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)
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}).0
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})
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|> list.reduce(int.add)
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|> result.unwrap(0)
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}