2023 Day 7 Part 1

2023/day07.nim

@@ -0,0 +1,82 @@
+import std/algorithm
+import std/enumerate
+import std/math
+import std/sequtils
+import std/sets
+import std/strscans
+import std/strutils
+import std/sugar
+import std/tables
+
+type Hand = tuple
+  cards: seq[int]
+  bid: int
+
+func parseCard(c: char): int =
+  case c:
+    of 'A': 14
+    of 'K': 13
+    of 'Q': 12
+    of 'J': 11
+    of 'T': 10
+    of '9': 9
+    of '8': 8
+    of '7': 7
+    of '6': 6
+    of '5': 5
+    of '4': 4
+    of '3': 3
+    of '2': 2
+    else: 0
+
+func parseHand(text: string): Hand =
+  let parts = text.strip.splitWhitespace
+  (parts[0].map(parseCard), parts[1].parseInt)
+
+func parseHands(text: string): seq[Hand] =
+  text.strip.splitLines.map(parseHand)
+
+func strength(hand: Hand): int =
+  let count = newCountTable(hand.cards)
+
+  var counts: CountTable[int]
+  for v in values(count):
+    counts.inc v
+
+  if counts[5] > 0:
+    return 7
+  if counts[4] > 0:
+    return 6
+  if counts[3] > 0:
+    if counts[2] > 0:
+      return 5
+    else:
+      return 4
+  if counts[2] == 2:
+    return 3
+  if counts[2] == 1:
+    return 2
+  return 1
+
+func cmpHand(a: Hand, b: Hand): int =
+  let strength = cmp(a.strength, b.strength)
+  if strength != 0:
+    return strength
+
+  for (aa, bb) in zip(a.cards, b.cards):
+    let card = cmp(aa, bb)
+    if card != 0:
+      return card
+
+proc dbg[T](v: T): T = (echo(v); v)
+
+proc part1(): int =
+  let text = readFile("input/day07.txt")
+  var hands = parseHands(text)
+
+  hands.sort(cmpHand)
+
+  for (rank, hand) in enumerate(hands):
+    result += (rank + 1) * hand.bid
+
+echo part1()