From ca613a0315569d14f0fc3ccecc263bbedc06c47a Mon Sep 17 00:00:00 2001
From: Jeremy Kaplan <jdkaplan@metagram.net>
Date: Sun, 3 Dec 2023 21:18:34 -0800
Subject: [PATCH] 2023 Day 4 Part 1

---
 2023/day04.nim | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 2023/day04.nim

diff --git a/2023/day04.nim b/2023/day04.nim
new file mode 100644
index 0000000..7742b2c
--- /dev/null
+++ b/2023/day04.nim
@@ -0,0 +1,45 @@
+import std/enumerate
+import std/math
+import std/sequtils
+import std/sets
+import std/strscans
+import std/strutils
+import std/tables
+
+type Card = tuple
+  id: int
+  winning: HashSet[int]
+  mine: HashSet[int]
+
+proc parseCard(line: string): Card =
+  var winning, mine: string
+  if not scanf(line, "Card$s$i: $* | $*$.", result.id, winning, mine):
+    raise newException(ValueError, line)
+
+  for num in winning.strip.splitWhitespace:
+    result.winning.incl num.parseInt
+
+  for num in mine.strip.splitWhitespace:
+    result.mine.incl num.parseInt
+
+proc parseCards(text: string): seq[Card] =
+  let lines = text.strip.splitLines()
+
+  for line in lines:
+    result.add parseCard(line)
+
+func score(card: Card): int =
+  let matches = len(card.winning * card.mine)
+  if matches > 0:
+    2 ^ (matches - 1)
+  else:
+    0
+
+proc part1(): int =
+  let text = readFile("input/day04.txt")
+  let cards = parseCards(text)
+
+  for card in cards:
+    result.inc card.score
+
+echo part1()