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import gleam/io
import gleam/int
import gleam/list
import gleam/string as str
import ext/resultx as resx
import util/input_util
type Expr {
Add(Expr, Expr)
Mul(Expr, Expr)
Literal(Int)
}
// digit = "0" | "1" | ... | "9" .
// op = "+" | "*" .
// Part 1
// p_expr = p_factor { op p_factor } .
// p_factor = "(" p_expr ")" | digit .
fn p_factor(text: String) -> #(Expr, String) {
let assert Ok(#(grapheme, text)) = str.pop_grapheme(text)
case grapheme {
"(" -> {
let #(expr, text) = p_expr(text)
let assert Ok(#(")", text)) = str.pop_grapheme(text)
#(expr, text)
}
digit -> #(Literal(resx.assert_unwrap(int.parse(digit))), text)
}
}
fn p_expr_tail(head: Expr, text: String) -> #(Expr, String) {
case str.pop_grapheme(text) {
Error(Nil) | Ok(#(")", _)) -> #(head, text)
Ok(#("+", text)) -> {
let #(factor, text) = p_factor(text)
p_expr_tail(Add(head, factor), text)
}
Ok(#("*", text)) -> {
let #(factor, text) = p_factor(text)
p_expr_tail(Mul(head, factor), text)
}
_ -> panic
}
}
fn p_expr(text: String) -> #(Expr, String) {
let #(factor, text) = p_factor(text)
p_expr_tail(factor, text)
}
// Part 2
// p_mul = p_add { "*" p_add } .
// p_add = p_term { "+" p_term } .
// p_term = "(" p_mul ")" | digit .
fn p_term(text: String) -> #(Expr, String) {
let assert Ok(#(grapheme, text)) = str.pop_grapheme(text)
case grapheme {
"(" -> {
let #(expr, text) = p_mul(text)
let assert Ok(#(")", text)) = str.pop_grapheme(text)
#(expr, text)
}
digit -> #(Literal(resx.assert_unwrap(int.parse(digit))), text)
}
}
fn p_add_tail(head: Expr, text: String) -> #(Expr, String) {
case str.pop_grapheme(text) {
Error(Nil) | Ok(#(")", _)) | Ok(#("*", _)) -> #(head, text)
Ok(#("+", text)) -> {
let #(term, text) = p_term(text)
p_add_tail(Add(head, term), text)
}
_ -> panic
}
}
fn p_add(text: String) -> #(Expr, String) {
let #(term, text) = p_term(text)
p_add_tail(term, text)
}
fn p_mul_tail(head: Expr, text: String) -> #(Expr, String) {
case str.pop_grapheme(text) {
Error(Nil) | Ok(#(")", _)) -> #(head, text)
Ok(#("*", text)) -> {
let #(add, text) = p_add(text)
p_mul_tail(Mul(head, add), text)
}
_ -> panic
}
}
fn p_mul(text: String) -> #(Expr, String) {
let #(add, text) = p_add(text)
p_mul_tail(add, text)
}
fn eval(expr: Expr) -> Int {
case expr {
Add(left, right) -> eval(left) + eval(right)
Mul(left, right) -> eval(left) * eval(right)
Literal(number) -> number
}
}
fn solve(lines: List(String), parser: fn(String) -> #(Expr, String)) {
lines
|> list.map(with: fn(text) {
let assert #(expr, "") =
text
|> str.replace(each: " ", with: "")
|> parser
eval(expr)
})
|> int.sum
}
fn part1(lines: List(String)) -> Int {
solve(lines, p_expr)
}
fn part2(lines: List(String)) -> Int {
solve(lines, p_mul)
}
pub fn main() -> Nil {
let assert 71 = part1(["1 + 2 * 3 + 4 * 5 + 6"])
let assert 51 = part1(["1 + (2 * 3) + (4 * (5 + 6))"])
let assert 26 = part1(["2 * 3 + (4 * 5)"])
let assert 437 = part1(["5 + (8 * 3 + 9 + 3 * 4 * 3)"])
let assert 12_240 = part1(["5 * 9 * (7 * 3 * 3 + 9 * 3 + (8 + 6 * 4))"])
let assert 13_632 = part1(["((2 + 4 * 9) * (6 + 9 * 8 + 6) + 6) + 2 + 4 * 2"])
let assert 231 = part2(["1 + 2 * 3 + 4 * 5 + 6"])
let assert 51 = part2(["1 + (2 * 3) + (4 * (5 + 6))"])
let assert 46 = part2(["2 * 3 + (4 * 5)"])
let assert 1445 = part2(["5 + (8 * 3 + 9 + 3 * 4 * 3)"])
let assert 669_060 = part2(["5 * 9 * (7 * 3 * 3 + 9 * 3 + (8 + 6 * 4))"])
let assert 23_340 = part2(["((2 + 4 * 9) * (6 + 9 * 8 + 6) + 6) + 2 + 4 * 2"])
let input = input_util.read_lines("day18")
io.debug(part1(input))
io.debug(part2(input))
Nil
}
|
