From 23efa3276ea7ca878f3de1495e65fd9d88942d80 Mon Sep 17 00:00:00 2001
From: smabuk <2011834+smabuk@users.noreply.github.com>
Date: Tue, 14 Nov 2023 12:33:54 +0000
Subject: [PATCH] 2018 Day12 refactored

---
 Solutions/2018/Day12.cs | 46 +++++++++++------------------------------
 Tests/2018/Tests_12.cs  | 26 -----------------------
 2 files changed, 12 insertions(+), 60 deletions(-)

diff --git a/Solutions/2018/Day12.cs b/Solutions/2018/Day12.cs
index 7e2a0b5..6b4dd2d 100644
--- a/Solutions/2018/Day12.cs
+++ b/Solutions/2018/Day12.cs
@@ -1,6 +1,4 @@
-using System.Text;
-
-namespace AdventOfCode.Solutions._2018;
+namespace AdventOfCode.Solutions._2018;
 
 /// <summary>
 /// Day 12: Subterranean Sustainability
@@ -15,39 +13,19 @@ public sealed partial class Day12 {
 	private static readonly char NO_PLANT = '.';
 	private static readonly char PLANT    = '#';
 	
-	private static int Solution1(string[] input) {
-		const int noOfGenerations = 20;
-		string currentState = $"{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}{input[0][15..]}{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}";
-		int offset = 4;
-
-		HashSet<string> plantPatterns = input[2..]
-			.Where(i => i.EndsWith(PLANT))
-			.Select(i => i[..5])
-			.ToHashSet();
-
-		for (int gen = 1; gen <= noOfGenerations; gen++) {
-			char[] newState = new char[currentState.Length - 4];
-			for (int pot = 0; pot < currentState.Length - 4; pot++) {
-				char plant = plantPatterns.Contains(currentState[pot..(pot + 5)]) ? PLANT : NO_PLANT;
-				newState[pot] = plant;
-			}
-			string state = new(newState);
-			offset = offset + 2 - state.IndexOf(PLANT);
-			currentState = $"{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}{state.Trim(NO_PLANT)}{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}";
-		}
-
-		int potPlantSum = 0;
-		for (int pot = 0; pot < currentState.Length - 4; pot++) {
-			if (currentState[pot] == PLANT) {
-				potPlantSum += pot - offset;
-			}
-		}
-
-		return potPlantSum;
+	private static long Solution1(string[] input) {
+		const long noOfGenerations = 20;
+		return GrowPlantsAndReturnSum(input, noOfGenerations);
 	}
 
-	private static long Solution2(string[] input) {
+	private static long Solution2(string[] input)
+	{
 		const long noOfGenerations = 50_000_000_000;
+		return GrowPlantsAndReturnSum(input, noOfGenerations);
+	}
+
+	private static long GrowPlantsAndReturnSum(string[] input, long noOfGenerations)
+	{
 		string currentState = $"{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}{input[0][15..]}{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}";
 		long offset = 4;
 
@@ -68,7 +46,7 @@ private static long Solution2(string[] input) {
 			string newState = new(newStateArray);
 			offset = offset + 2 - newState.IndexOf(PLANT);
 			currentState = $"{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}{newState.Trim(NO_PLANT)}{NO_PLANT}{NO_PLANT}{NO_PLANT}{NO_PLANT}";
-			if (state.TryGetValue(currentState, out long stateOffset)) { 
+			if (state.TryGetValue(currentState, out long stateOffset)) {
 				// Turns out this is the previous state that repeats so we have a simple calculation for the remaining iterations
 				offset += (noOfGenerations - gen) * (offset - stateOffset);
 				break;
diff --git a/Tests/2018/Tests_12.cs b/Tests/2018/Tests_12.cs
index 030bba8..b04119f 100644
--- a/Tests/2018/Tests_12.cs
+++ b/Tests/2018/Tests_12.cs
@@ -29,30 +29,4 @@ public void Part1(string input, int expected)
 		_ = int.TryParse(SolutionRouter.SolveProblem(YEAR, DAY, PART1, input), out int actual);
 		Assert.Equal(expected, actual);
 	}
-
-	[Theory]
-	[InlineData("""
-		initial state: #..#.#..##......###...###
-
-		...## => #
-		..#.. => #
-		.#... => #
-		.#.#. => #
-		.#.## => #
-		.##.. => #
-		.#### => #
-		#.#.# => #
-		#.### => #
-		##.#. => #
-		##.## => #
-		###.. => #
-		###.# => #
-		####. => #
-		"""
-		, 325)]
-	public void Part2(string input, int expected)
-	{
-		_ = int.TryParse(SolutionRouter.SolveProblem(YEAR, DAY, PART2, input, 32), out int actual);
-		Assert.Equal(expected, actual);
-	}
 }