4 files changed, 186 insertions, 0 deletions
diff --git a/aoc2017-gleam/src/aoc_2017/day_4.gleam b/aoc2017-gleam/src/aoc_2017/day_4.gleam
new file mode 100644
index 0000000..9bc4f9a
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_4.gleam
@@ -0,0 +1,31 @@
+import gleam/list
+import gleam/string
+
+pub fn parse(input: String) -> List(List(String)) {
+  use row <- list.map(string.split(input, "\n"))
+  string.split(row, " ")
+}
+
+pub fn pt_1(input: List(List(String))) {
+  use acc, passwords <- list.fold(input, 0)
+  case passwords == list.unique(passwords) {
+    True -> acc + 1
+    False -> acc
+  }
+}
+
+pub fn pt_2(input: List(List(String))) {
+  use acc, passwords <- list.fold(input, 0)
+  let sorted_passwords = list.map(passwords, sort_graphemes)
+  case sorted_passwords == list.unique(sorted_passwords) {
+    True -> acc + 1
+    False -> acc
+  }
+}
+
+fn sort_graphemes(word: String) -> String {
+  word
+  |> string.to_graphemes
+  |> list.sort(string.compare)
+  |> string.concat
+}
diff --git a/aoc2017-gleam/src/aoc_2017/day_5.gleam b/aoc2017-gleam/src/aoc_2017/day_5.gleam
new file mode 100644
index 0000000..a0b9b80
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_5.gleam
@@ -0,0 +1,48 @@
+import gary.{type ErlangArray}
+import gary/array
+import gleam/int
+import gleam/list
+import gleam/result
+import gleam/string
+
+pub fn parse(input: String) -> ErlangArray(Int) {
+  input
+  |> string.split("\n")
+  |> list.map(int.parse)
+  |> result.values()
+  |> array.from_list(default: 0)
+  |> array.make_fixed()
+}
+
+pub fn pt_1(input: ErlangArray(Int)) {
+  next_step(input, 0, 0, part: 1)
+}
+
+pub fn pt_2(input: ErlangArray(Int)) {
+  next_step(input, 0, 0, part: 2)
+}
+
+fn next_step(
+  instructions: ErlangArray(Int),
+  pointer: Int,
+  step: Int,
+  part part: Int,
+) {
+  case array.get(from: instructions, at: pointer) {
+    Ok(distance) -> {
+      let delta = delta(distance, part)
+      let assert Ok(updated_instructions) =
+        array.set(instructions, at: pointer, put: distance + delta)
+      next_step(updated_instructions, pointer + distance, step + 1, part)
+    }
+    Error(_) -> step
+  }
+}
+
+fn delta(d: Int, part: Int) {
+  case part, d {
+    1, _ -> 1
+    _, n if n < 3 -> 1
+    _, _ -> -1
+  }
+}
diff --git a/aoc2017-gleam/src/aoc_2017/day_6.gleam b/aoc2017-gleam/src/aoc_2017/day_6.gleam
new file mode 100644
index 0000000..84222e1
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_6.gleam
@@ -0,0 +1,65 @@
+import gary.{type ErlangArray}
+import gary/array
+import gleam/bool
+import gleam/int
+import gleam/list
+import gleam/result
+import gleam/set.{type Set}
+import gleam/string
+
+pub fn parse(input) -> ErlangArray(Int) {
+  input
+  |> string.split("\t")
+  |> list.map(int.parse)
+  |> result.values()
+  |> array.from_list(default: -1)
+  |> array.make_fixed()
+}
+
+pub fn pt_1(input: ErlangArray(Int)) {
+  check_cycle(input, set.from_list([input]), 1).1
+}
+
+pub fn pt_2(input: ErlangArray(Int)) {
+  let #(target, cycle) = check_cycle(input, set.from_list([input]), 1)
+  cycle - check_cycle(input, set.from_list([input, target]), 1).1
+}
+
+fn get_max(array: ErlangArray(Int)) -> #(Int, Int) {
+  use index, value, max <- array.fold(over: array, from: #(-1, -1))
+  case value > max.1 {
+    True -> #(index, value)
+    False -> max
+  }
+}
+
+fn redistribute(
+  array: ErlangArray(Int),
+  pointer: Int,
+  remaining: Int,
+) -> ErlangArray(Int) {
+  use <- bool.guard(remaining == 0, array)
+  case array.get(from: array, at: pointer) {
+    Error(_) -> redistribute(array, 0, remaining)
+    Ok(n) -> {
+      let assert Ok(updated_array) =
+        array.set(into: array, at: pointer, put: n + 1)
+      redistribute(updated_array, pointer + 1, remaining - 1)
+    }
+  }
+}
+
+fn check_cycle(
+  current: ErlangArray(Int),
+  cache: Set(ErlangArray(Int)),
+  cycle: Int,
+) -> #(ErlangArray(Int), Int) {
+  let #(index, to_redistribute) = current |> get_max
+  let assert Ok(zeroed) = array.set(into: current, at: index, put: 0)
+  let next = redistribute(zeroed, index + 1, to_redistribute)
+
+  case set.contains(cache, next) {
+    True -> #(next, cycle)
+    False -> check_cycle(next, set.insert(cache, next), cycle + 1)
+  }
+}
diff --git a/aoc2017-gleam/src/aoc_2017/day_7.gleam b/aoc2017-gleam/src/aoc_2017/day_7.gleam
new file mode 100644
index 0000000..593282b
--- /dev/null
+++ b/aoc2017-gleam/src/aoc_2017/day_7.gleam
@@ -0,0 +1,42 @@
+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"
+}