Slooowwww day 14

answers/14.txt

@@ -0,0 +1,2 @@
+2776141917
+20331097

data/14.txt

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+598701

day14.nim

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+import sequtils, strutils
+
+let
+    input = readFile("data/14.txt").strip
+    inputSeq = input.map do (c: char) -> int: cast[int](c) - 48
+    lastDigit = inputSeq[inputSeq.len - 1]
+    inputInt = input.parseInt
+
+var
+    scores = newSeq[int](100_000_000)  # Arbitrary large preallocation
+    size = 2
+    elf1 = 0
+    elf2 = 1
+    part2 = -1
+
+scores[0] = 3
+scores[1] = 7
+
+while size < inputInt + 10 or part2 == -1:
+    var score = scores[elf1] + scores[elf2]
+    
+    if score >= 10:
+        let newScore = score div 10
+        scores[size] = newScore
+        size.inc
+
+        if newScore == lastDigit and size > input.len and scores[size-input.len..size-1] == inputSeq:
+            part2 = size - input.len
+
+    let newScore = score mod 10
+    scores[size] = newScore
+    size.inc
+
+    if newScore == lastDigit and size > input.len and scores[size-input.len..size-1] == inputSeq:
+        part2 = size - input.len
+
+    elf1 = (elf1 + scores[elf1] + 1) mod size
+    elf2 = (elf2 + scores[elf2] + 1) mod size
+
+echo scores[inputInt..inputInt+9].join
+echo part2