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This commit is contained in:
Shadowfacts 2018-12-03 16:58:13 -05:00
parent 16f5505974
commit ad6c796cd2
Signed by: shadowfacts
GPG Key ID: 94A5AB95422746E5
5 changed files with 105 additions and 83 deletions
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51
lib/day1/day1.ex
View File

@ -1,7 +1,7 @@
defmodule Day1 do
def calculate_frequency(shifts) do
shifts
|> Enum.reduce(0, &+/2)
|> Enum.reduce(0, &+/2)
end
def first_repetition(shifts, index \\ 0, sum \\ 0, seen \\ [0]) do
@ -11,6 +11,7 @@ defmodule Day1 do
cond do
Enum.member?(seen, sum) ->
sum
true ->
first_repetition(shifts, next_index, sum, [sum | seen])
end
@ -18,44 +19,46 @@ defmodule Day1 do
def first_repetition_stream(shifts) do
shifts
|> Stream.cycle()
|> Enum.reduce_while({0, [0]}, fn shift, {sum, seen} ->
sum = sum + shift
cond do
Enum.member?(seen, sum) -> {:halt, sum}
true -> {:cont, {sum, [sum | seen]}}
end
end)
|> Stream.cycle()
|> Enum.reduce_while({0, [0]}, fn shift, {sum, seen} ->
sum = sum + shift
cond do
Enum.member?(seen, sum) -> {:halt, sum}
true -> {:cont, {sum, [sum | seen]}}
end
end)
end
def first_repetition_mapset(shifts) do
shifts
|> Stream.cycle()
|> Enum.reduce_while({0, MapSet.new([0])}, fn shift, {sum, seen} ->
sum = sum + shift
cond do
sum in seen -> {:halt, sum}
true -> {:cont, {sum, MapSet.put(seen, sum)}}
end
end)
|> Stream.cycle()
|> Enum.reduce_while({0, MapSet.new([0])}, fn shift, {sum, seen} ->
sum = sum + shift
cond do
sum in seen -> {:halt, sum}
true -> {:cont, {sum, MapSet.put(seen, sum)}}
end
end)
end
def parse_input() do
File.read!("lib/day1/input.txt")
|> String.split("\n")
|> Enum.map(fn s ->
{num, _} = Integer.parse(s)
num
end)
|> String.split("\n")
|> Enum.map(fn s ->
{num, _} = Integer.parse(s)
num
end)
end
def part1() do
parse_input()
|> calculate_frequency()
|> calculate_frequency()
end
def part2() do
parse_input()
|> first_repetition_mapset()
|> first_repetition_mapset()
end
end

48
lib/day2/day2.ex
View File

@ -1,10 +1,10 @@
defmodule Day2 do
def count_characters(id) do
id
|> String.graphemes()
|> Enum.reduce(%{}, fn c, acc ->
Map.update(acc, c, 1, &(&1 + 1))
end)
|> String.graphemes()
|> Enum.reduce(%{}, fn c, acc ->
Map.update(acc, c, 1, &(&1 + 1))
end)
end
def checksum(list) do
@ -17,23 +17,25 @@ defmodule Day2 do
defp any_char_count(n) do
fn map ->
map
|> Enum.to_list()
|> Enum.any?(fn {_c, count} -> count == n end)
|> Enum.to_list()
|> Enum.any?(fn {_c, count} -> count == n end)
end
end
def diff(a, b) do
a = String.graphemes(a)
b = String.graphemes(b)
Enum.zip(a, b)
|> Enum.reduce({0, ""}, fn {a, b}, {diff_count, common} ->
cond do
a == b ->
{diff_count, common <> a}
true ->
{diff_count + 1, common}
end
end)
|> Enum.reduce({0, ""}, fn {a, b}, {diff_count, common} ->
cond do
a == b ->
{diff_count, common <> a}
true ->
{diff_count + 1, common}
end
end)
end
def match(id, list) do
@ -47,12 +49,12 @@ defmodule Day2 do
def correct_boxes(list) do
list
|> Enum.reduce_while(nil, fn id, _acc ->
case match(id, list) do
nil -> {:cont, nil}
common -> {:halt, common}
end
end)
|> Enum.reduce_while(nil, fn id, _acc ->
case match(id, list) do
nil -> {:cont, nil}
common -> {:halt, common}
end
end)
end
def except(list, except) do
@ -61,16 +63,16 @@ defmodule Day2 do
defp parse_input() do
File.read!("lib/day2/input.txt")
|> String.split("\n")
|> String.split("\n")
end
def part1() do
parse_input()
|> checksum()
|> checksum()
end
def part2() do
parse_input()
|> correct_boxes()
|> correct_boxes()
end
end

66
lib/day3/day3.ex
View File

@ -1,11 +1,12 @@
defmodule Day3 do
defmodule Rect do
defstruct [:id, :left, :top, :width, :height]
def points(nil), do: []
def points(rect) do
xs = rect.left..(rect.left + rect.width - 1)
Enum.flat_map(xs, fn x ->
ys = rect.top..(rect.top + rect.height - 1)
Enum.map(ys, fn y -> {x, y} end)
@ -14,26 +15,34 @@ defmodule Day3 do
def overlap(a, b) do
overlap_left = max(a.left, b.left)
overlap_width = max(0, min(a.left + a.width, b.left + b.width) - overlap_left)
overlap_width = max(0, min(a.left + a.width, b.left + b.width) - overlap_left)
overlap_top = max(a.top, b.top)
overlap_height = max(0, min(a.top + a.height, b.top + b.height) - overlap_top)
case overlap_width * overlap_height do
0 ->
nil
_ ->
%Rect{left: overlap_left, top: overlap_top, width: overlap_width, height: overlap_height}
%Rect{
left: overlap_left,
top: overlap_top,
width: overlap_width,
height: overlap_height
}
end
end
end
def parse_rect(str) do
parts = Regex.run(~r/#(\d+) @ (\d+),(\d+): (\d+)x(\d+)/, str)
%Rect{
id: parts |> Enum.at(1) |> String.to_integer,
left: parts |> Enum.at(2) |> String.to_integer,
top: parts |> Enum.at(3) |> String.to_integer,
width: parts |> Enum.at(4) |> String.to_integer,
height: parts |> Enum.at(5) |> String.to_integer,
id: parts |> Enum.at(1) |> String.to_integer(),
left: parts |> Enum.at(2) |> String.to_integer(),
top: parts |> Enum.at(3) |> String.to_integer(),
width: parts |> Enum.at(4) |> String.to_integer(),
height: parts |> Enum.at(5) |> String.to_integer()
}
end
@ -43,44 +52,43 @@ defmodule Day3 do
def overlap_area(rects) do
rects
|> Enum.flat_map(fn rect ->
rects
|> except(rect)
|> Enum.map(fn other ->
Rect.overlap(rect, other)
end)
|> Enum.flat_map(&Rect.points/1)
|> Enum.flat_map(fn rect ->
rects
|> except(rect)
|> Enum.map(fn other ->
Rect.overlap(rect, other)
end)
|> Enum.uniq
|> Enum.count
|> Enum.flat_map(&Rect.points/1)
end)
|> Enum.uniq()
|> Enum.count()
end
def exclude_overlapping(rects) do
rects
|> Enum.reject(fn rect ->
rects
|> except(rect)
|> Enum.any?(fn other ->
Rect.overlap(rect, other) != nil
end)
|> Enum.reject(fn rect ->
rects
|> except(rect)
|> Enum.any?(fn other ->
Rect.overlap(rect, other) != nil
end)
end)
end
def parse_input() do
File.read!("lib/day3/input.txt")
|> String.split("\n", trim: true)
|> String.split("\n", trim: true)
end
def part1() do
parse_input()
|> Enum.map(&parse_rect/1)
|> overlap_area()
|> Enum.map(&parse_rect/1)
|> overlap_area()
end
def part2() do
parse_input()
|> Enum.map(&parse_rect/1)
|> exclude_overlapping()
|> Enum.map(&parse_rect/1)
|> exclude_overlapping()
end
end

10
test/day2_test.exs
View File

@ -3,7 +3,15 @@ defmodule Day2Test do
doctest Day2
test "count characters" do
assert Day2.count_characters("abcdef") == %{"a" => 1, "b" => 1, "c" => 1, "d" => 1, "e" => 1, "f" => 1}
assert Day2.count_characters("abcdef") == %{
"a" => 1,
"b" => 1,
"c" => 1,
"d" => 1,
"e" => 1,
"f" => 1
}
assert Day2.count_characters("bababc") == %{"a" => 2, "b" => 3, "c" => 1}
assert Day2.count_characters("abbcde") == %{"a" => 1, "b" => 2, "c" => 1, "d" => 1, "e" => 1}
end

3
test/day3_test.exs
View File

@ -25,6 +25,7 @@ defmodule Day3Test do
%Rect{id: 2, left: 3, top: 1, width: 4, height: 4},
%Rect{id: 3, left: 5, top: 5, width: 2, height: 2}
]
assert Day3.overlap_area(rects) == 4
end
@ -34,9 +35,9 @@ defmodule Day3Test do
%Rect{id: 2, left: 3, top: 1, width: 4, height: 4},
%Rect{id: 3, left: 5, top: 5, width: 2, height: 2}
]
res = Day3.exclude_overlapping(rects)
assert Enum.count(res) == 1
assert Enum.at(res, 0).id == 3
end
end