From 918aaab8a65a5c4aff89333a3de417ac0c4369a8 Mon Sep 17 00:00:00 2001
From: Shanti Chellaram <shanti@shanti.im>
Date: Sat, 3 Dec 2022 13:11:36 +0900
Subject: [PATCH] Day 2-1

---
 day2.erl | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 day2.erl

diff --git a/day2.erl b/day2.erl
new file mode 100644
index 0000000..86f0418
--- /dev/null
+++ b/day2.erl
@@ -0,0 +1,31 @@
+-module(day2).
+
+-export([solve/1]).
+
+solve(InputData) ->
+	RoundData = binary:split(InputData, <<$\n>>, [trim_all, global]),
+	Rounds = lists:map(fun parse_round/1, RoundData),
+	RoundPoints = lists:map(fun score_round/1, Rounds),
+	{lists:sum(RoundPoints), none}.
+
+parse_round(<<TheirCode, $\s, YourCode>>) -> {parse_theirs(TheirCode), parse_yours(YourCode)}.
+
+score_round(Round = {_Theirs, Yours}) -> round_points(Round) + shape_points(Yours).
+
+parse_theirs($A) -> rock;
+parse_theirs($B) -> paper;
+parse_theirs($C) -> scissors.
+
+parse_yours($X) -> rock;
+parse_yours($Y) -> paper;
+parse_yours($Z) -> scissors.
+
+round_points({rock, paper}) -> 6;
+round_points({paper, scissors}) -> 6;
+round_points({scissors, rock}) -> 6;
+round_points({Shape, Shape}) -> 3;
+round_points({_Theirs, _Yours}) -> 0.
+
+shape_points(rock) -> 1;
+shape_points(paper) -> 2;
+shape_points(scissors) -> 3.