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import gleam/int
import gleam/io
import gleam/list
import gleam/option.{None, Some}
import gleam/regex.{type Match, Match}
import gleam/set
import gleam/string
pub type Program {
Program(name: String, weight: Int, supporting: List(String))
}
pub fn parse(input: String) {
let assert Ok(re) = regex.from_string("([a-z]+) \\(([0-9]+)\\)(?> -> (.*))?")
use match <- list.map(string.split(input, "\n"))
case regex.scan(re, match) {
[Match(submatches: [Some(name), Some(weight)], ..)] ->
Program(name, to_int(weight), [])
[Match(submatches: [Some(name), Some(weight), Some(supporting)], ..)] ->
Program(name, to_int(weight), string.split(supporting, ", "))
_ -> panic as { "couldn't parse" <> match }
}
}
fn to_int(str: String) -> Int {
let assert Ok(n) = int.parse(str)
n
}
pub fn pt_1(input: List(Program)) {
let supporters = input |> list.map(fn(p) { p.name }) |> set.from_list()
let supporting =
input |> list.flat_map(fn(p) { p.supporting }) |> set.from_list()
let assert [base] = set.difference(supporters, supporting) |> set.to_list
base
}
pub fn pt_2(input: List(Program)) {
todo as "part 2 not implemented"
}
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