aoc-all

commit 894d2b1f2c3e4bc12fa95d574a8e695d5bcf05f1
parent c1f229bec1b84a4759dbbae19f198d47d3ce3ce3
Author: Natasha Kerensikova <natgh@instinctive.eu>
Date:   Sun, 22 Dec 2024 18:22:04 +0000

Day 22 references and solutions
Diffstat:
A
2024/day22.nim
 | 
70
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
2024/ref/day22a.txt
 | 
4
++++
A
2024/ref/day22b.txt
 | 
4
++++

3 files changed, 78 insertions(+), 0 deletions(-)
diff --git a/2024/day22.nim b/2024/day22.nim
@@ -0,0 +1,70 @@
+# Copyright (c) 2024, Natacha Porté
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+from std/sequtils import foldl, map, mapIt, toSeq, zip
+from std/strutils import parseInt
+from std/tables   import `[]`, `[]=`, getOrDefault, hasKey, pairs, Table
+
+# Read input file
+
+let data = stdin.lines().toSeq().map(parseInt)
+
+# Puzzle 1
+
+func step(n: int): int =
+  let
+    s1 = ((n * 64) xor n) mod 16777216
+    s2 = ((s1 div 32) xor s1) mod 16777216
+    s3 = ((s2 * 2048) xor s2) mod 16777216
+  result = s3
+
+let test_data = @[123, 15887950, 16495136, 527345, 704524, 1553684, 12683156, 11100544, 12249484, 7753432, 5908254]
+
+for (a,b) in zip(test_data[0 .. ^2], test_data[1 .. ^1]):
+  assert step(a) == b
+
+func steps(n, s: int): int =
+  result = n
+  for i in 1 .. s:
+    result = step(result)
+
+echo "Puzzle 1: ", data.mapIt(steps(it, 2000)).foldl(a + b)
+
+# Puzzle 2
+
+var scores: Table[seq[int], int]
+var max_score = 0
+
+for seed in data:
+  let
+    s1 = step(seed)
+    s2 = step(s1)
+    s3 = step(s2)
+  var
+    last = s3
+    d = @[0, (s1 mod 10) - (seed mod 10), (s2 mod 10) - (s1 mod 10), (s3 mod 10) - (s2 mod 10)]
+
+  var seen: Table[seq[int], bool]
+  for i in 4 .. 2000:
+    let next = step(last)
+    d = d[1 .. ^1]
+    d.add((next mod 10) - (last mod 10))
+    if not seen.hasKey(d):
+      seen[d] = true
+      let new_score = scores.getOrDefault(d, 0) + (next mod 10)
+      scores[d] = new_score
+      max_score = max(max_score, new_score)
+    last = next
+
+echo "Puzzle 2: ", max_score
diff --git a/2024/ref/day22a.txt b/2024/ref/day22a.txt
@@ -0,0 +1,4 @@
+1
+10
+100
+2024
diff --git a/2024/ref/day22b.txt b/2024/ref/day22b.txt
@@ -0,0 +1,4 @@
+1
+2
+3
+2024