Solve day 1 of 2020 in Gleam

1 files changed, 34 insertions, 0 deletions

diff --git a/aoc-2020-gleam/src/days/day01.gleam b/aoc-2020-gleam/src/days/day01.gleam
new file mode 100644
index 0000000..6e75826
--- /dev/null
+++ b/aoc-2020-gleam/src/days/day01.gleam
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+import gleam/io
+import gleam/int
+import gleam/list
+import gleam/result
+import ext/resultx
+import util/input_util
+
+fn solve(numbers: List(Int), n: Int) -> Int {
+  numbers
+  |> list.combinations(by: n)
+  |> list.find(one_that: fn(p) { int.sum(p) == 2020 })
+  |> result.map(with: int.product)
+  |> resultx.force_unwrap()
+}
+
+fn part1(numbers: List(Int)) -> Int {
+  solve(numbers, 2)
+}
+
+fn part2(numbers: List(Int)) -> Int {
+  solve(numbers, 3)
+}
+
+pub fn run() -> Nil {
+  let test = input_util.read_numbers("test01")
+  assert 514_579 = part1(test)
+  assert 241_861_950 = part2(test)
+
+  let input = input_util.read_numbers("day01")
+  io.debug(part1(input))
+  io.debug(part2(input))
+
+  Nil
+}