day 6 gleam/racket complete

4 files changed, 167 insertions, 0 deletions

diff --git a/aoc2023-other/day-06/day-06.rkt b/aoc2023-other/day-06/day-06.rkt
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--- /dev/null
+++ b/aoc2023-other/day-06/day-06.rkt
@@ -0,0 +1,31 @@
+#lang racket
+
+(require advent-of-code
+         threading)
+
+(match-define (list times distances)
+  (~> (open-aoc-input (find-session) 2023 6 #:cache #true) port->lines))
+
+;; part 1
+(define get-numbers (λ~> string-split (map string->number _) rest))
+(define (find-bound race-time dist button-time step)
+  (if (< dist (* button-time (- race-time button-time)))
+      button-time
+      (find-bound race-time dist (+ step button-time) step)))
+
+(define (lower-bound rtime dist)
+  (find-bound rtime dist 1 1))
+(define (upper-bound rtime dist)
+  (find-bound rtime dist rtime -1))
+
+(for/fold ([acc 1])
+          ([race-time (in-list (get-numbers times))] [distance (in-list (get-numbers distances))])
+  (* acc (add1 (- (upper-bound race-time distance) (lower-bound race-time distance)))))
+
+;; part 2
+
+(define unkern (λ~>> get-numbers (apply ~a) string->number))
+(define big-time (unkern times))
+(define big-distance (unkern distances))
+
+(add1 (- (upper-bound big-time big-distance) (lower-bound big-time big-distance)))
diff --git a/aoc2023/src/day6/.gitignore b/aoc2023/src/day6/.gitignore
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index 0000000..ae40cea
--- /dev/null
+++ b/aoc2023/src/day6/.gitignore
@@ -0,0 +1 @@
+input.txt
\ No newline at end of file
diff --git a/aoc2023/src/day6/solve.gleam b/aoc2023/src/day6/solve.gleam
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index 0000000..98f39a1
--- /dev/null
+++ b/aoc2023/src/day6/solve.gleam
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+import adglent.{First, Second}
+import gleam/io
+import gleam/string
+import gleam/int
+import gleam/list
+import gleam/result
+
+type Race {
+  Race(time: Int, distance: Int)
+}
+
+fn parse_with_bad_kerning(input: String) {
+  input
+  |> string.split("\n")
+  |> list.map(fn(str) {
+    str
+    |> string.split(" ")
+    |> list.map(int.parse)
+    |> result.values
+  })
+  |> list.transpose
+  |> list.map(fn(ns) {
+    let [t, d] = ns
+    Race(t, d)
+  })
+}
+
+fn find_bound(race: Race, button_time: Int, step: Int) {
+  let travel_time = race.time - button_time
+  case button_time * travel_time > race.distance {
+    True -> button_time
+    False -> find_bound(race, button_time + step, step)
+  }
+}
+
+fn lower_bound(race: Race) {
+  find_bound(race, 1, 1)
+}
+
+fn upper_bound(race: Race) {
+  find_bound(race, race.time, -1)
+}
+
+pub fn part1(input: String) {
+  {
+    use acc, race <- list.fold(parse_with_bad_kerning(input), 1)
+    acc * { upper_bound(race) - lower_bound(race) + 1 }
+  }
+  |> string.inspect
+}
+
+fn parse_properly(input: String) {
+  input
+  |> string.replace(" ", "")
+  |> string.split("\n")
+  |> list.flat_map(string.split(_, ":"))
+  |> list.map(int.parse)
+  |> result.values
+}
+
+pub fn part2(input: String) {
+  let [time, distance] =
+    input
+    |> parse_properly
+
+  let race = Race(time, distance)
+  
+  upper_bound(race) - lower_bound(race) + 1
+  |> string.inspect
+}
+
+pub fn main() {
+  let assert Ok(part) = adglent.get_part()
+  let assert Ok(input) = adglent.get_input("6")
+  case part {
+    First ->
+      part1(input)
+      |> adglent.inspect
+      |> io.println
+    Second ->
+      part2(input)
+      |> adglent.inspect
+      |> io.println
+  }
+}
diff --git a/aoc2023/test/day6/day6_test.gleam b/aoc2023/test/day6/day6_test.gleam
new file mode 100644
index 0000000..c551993
--- /dev/null
+++ b/aoc2023/test/day6/day6_test.gleam
@@ -0,0 +1,50 @@
+import gleam/list
+import showtime/tests/should
+import adglent.{type Example, Example}
+import day6/solve
+
+type Problem1AnswerType =
+  String
+
+type Problem2AnswerType =
+  String
+
+/// Add examples for part 1 here:
+/// ```gleam
+///const part1_examples: List(Example(Problem1AnswerType)) = [Example("some input", "")]
+/// ```
+const part1_examples: List(Example(Problem1AnswerType)) = [
+  Example(
+    "Time:      7  15   30
+Distance:  9  40  200",
+    "288",
+  ),
+]
+
+/// Add examples for part 2 here:
+/// ```gleam
+///const part2_examples: List(Example(Problem2AnswerType)) = [Example("some input", "")]
+/// ```
+const part2_examples: List(Example(Problem2AnswerType)) = [
+  Example(
+    "Time:      7  15   30
+Distance:  9  40  200",
+    "71503",
+  ),
+]
+
+pub fn part1_test() {
+  part1_examples
+  |> should.not_equal([])
+  use example <- list.map(part1_examples)
+  solve.part1(example.input)
+  |> should.equal(example.answer)
+}
+
+pub fn part2_test() {
+  part2_examples
+  |> should.not_equal([])
+  use example <- list.map(part2_examples)
+  solve.part2(example.input)
+  |> should.equal(example.answer)
+}