day04

2023/day04.nim

@@ -0,0 +1,45 @@
+import std/[math, sequtils, strutils, sugar]
+
+type
+  Card = object
+    winning, having: seq[int]
+
+proc toCard(line: string): Card =
+  let sp = line.split(':')[1].strip().split('|')
+  result.winning = sp[0].strip().splitWhitespace.map(parseInt)
+  result.having = sp[1].strip().splitWhitespace.map(parseInt)
+
+func winningNumbers(card: Card): seq[int] =
+  card.having.filterIt(it in card.winning)
+
+func points(winning: seq[int]): int =
+  if winning.len > 0:
+    2 ^ (winning.len - 1)
+  else:
+    0
+
+proc count(winning, cards: seq[int]): int =
+  # [4, 2, 2, 1,  0, 0]
+  # [1, 2, 4, 8, 14, 1]
+  result = 1
+  for _ in 1..winning[0]:
+    result += cards.count(winning[1..winning[0]])
+
+proc p1(input: string) =
+  echo input.splitLines().map(toCard).map(winningNumbers).map(points).sum()
+
+proc p2(input: string) =
+  let wins = input.splitLines().map(toCard).map(winningNumbers).mapIt(it.len)
+  var cards = collect:
+    for i in 0..wins.high:
+      1
+  for i, v in wins:
+    for j in 0..<cards[i]:
+      for k in 0..<v:
+        cards[i+k+1] += 1
+  echo cards.sum()
+
+when isMainModule:
+  let input = stdin.readAll().strip()
+  p1(input)
+  p2(input)