From c260de0841aab5a639400a84932cebec225c7a27 Mon Sep 17 00:00:00 2001
From: Stefan Forstenlechner <stefanforstenlechner@gmail.com>
Date: Tue, 14 Dec 2021 23:05:07 +0100
Subject: [PATCH] Day 14 minor cleanup

---
 Day14.cs | 70 +++++++++++++++++++++++---------------------------------
 1 file changed, 29 insertions(+), 41 deletions(-)

diff --git a/Day14.cs b/Day14.cs
index a5f27ca..612babb 100644
--- a/Day14.cs
+++ b/Day14.cs
@@ -1,35 +1,33 @@
 #define Day14
 #if Day14
 using System.Text.RegularExpressions;
-using AoC2021;
 var text = File.ReadAllText("day14/input").Split("\n\n");
-var startOne = text[0].Select(x => x).ToList();
-var startTwo = startOne.ToList();
+var start = text[0].Select(x => x).ToList();
 
 var reg = new Regex(@"(?<a>\w)(?<b>\w) -> (?<res>\w)");
 var rules = reg.Matches(text[1]).Select(m => new Rule(new Pair(m.Groups["a"].Value[0], m.Groups["b"].Value[0]), m.Groups["res"].Value[0])).ToDictionary(x => x.p, x=> x.res);
 
-// for (var i = 0; i < 10; i++) {
-//     var next = new List<char>();
-//     for (int pos = 1; pos < startOne.Count; pos++) {
-//         var res = rules[new Pair(startOne[pos - 1], startOne[pos])];
-//         next.Add(startOne[pos - 1]);
-//         next.Add(res);
-//     }
-//     next.Add(startOne.Last());
-//     startOne = next;
-// }
-//
-// var charCountPartOne = startOne.GroupBy(s => s).ToDictionary(g => g.Key, g => g.LongCount());
-// Console.WriteLine(charCountPartOne.Values.Max() - charCountPartOne.Values.Min());
-//
-// var charCountPartTwo = rules.Keys.SelectMany(r => new List<char>(){r.a, r.b}).Distinct().ToDictionary(x => x, _ => 0L);
-int maxDepth = 40;
+for (var i = 0; i < 10; i++) {
+    var next = new List<char>();
+    for (int pos = 1; pos < start.Count; pos++) {
+        var res = rules[new Pair(start[pos - 1], start[pos])];
+        next.Add(start[pos - 1]);
+        next.Add(res);
+    }
+    next.Add(start.Last());
+    start = next;
+}
 
-var finalCount = new Dictionary<char, long>();
+var charCountPartOne = start.GroupBy(s => s).ToDictionary(g => g.Key, g => g.LongCount());
+Console.WriteLine(charCountPartOne.Values.Max() - charCountPartOne.Values.Min());
+
+// Part two
+start = text[0].Select(x => x).ToList();
+int maxDepth = 40;
+var charCountPartTwo = new Dictionary<char, long>();
 var save = new Dictionary<AsKey, Dictionary<char, long>>();
 
-Dictionary<char, long> Bla(Pair cur, int depth) {
+Dictionary<char, long> Process(Pair cur, int depth) {
     var curKey = new AsKey(cur, depth);
     if (save.ContainsKey(curKey)) {
         return save[curKey];
@@ -39,8 +37,8 @@ Dictionary<char, long> Bla(Pair cur, int depth) {
     }
 
     var c = rules[cur];
-    var first = Bla(new Pair(cur.a, c), depth - 1);
-    var second = Bla(new Pair(c, cur.b), depth - 1);
+    var first = Process(new Pair(cur.a, c), depth - 1);
+    var second = Process(new Pair(c, cur.b), depth - 1);
 
     var merged = Merge(first, second);
     save[curKey] = merged.ToDictionary(x => x.Key, x => x.Value);
@@ -49,28 +47,18 @@ Dictionary<char, long> Bla(Pair cur, int depth) {
 }
 
 Dictionary<char, long> Merge(Dictionary<char, long> a, Dictionary<char, long> b) {
-    var merged = new Dictionary<char, long>();
-    foreach (var k in a.Keys) {
-        merged.Add(k, a[k]);
-    }
-    foreach (var k in b.Keys) {
-        if (merged.ContainsKey(k)) {
-            merged[k] += b[k];
-        } else {
-            merged[k] = b[k];
-        }
-    }
-
-    return merged;
+    return new List<Dictionary<char, long>>(){a, b}.SelectMany(x => x)
+        .ToLookup(pair => pair.Key, pair => pair.Value)
+        .ToDictionary(group => group.Key, group => group.Sum());
 }
 
-for (int pos = 1; pos < startTwo.Count; pos++) {
-    var countBla = Bla(new Pair(startTwo[pos - 1], startTwo[pos]), maxDepth);
-    finalCount = Merge(finalCount, countBla);
+for (int pos = 1; pos < start.Count; pos++) {
+    var countBla = Process(new Pair(start[pos - 1], start[pos]), maxDepth);
+    charCountPartTwo = Merge(charCountPartTwo, countBla);
 }
-finalCount[startTwo.Last()]++;
+charCountPartTwo[start.Last()]++;
 
-Console.WriteLine(finalCount.Values.Max() - finalCount.Values.Min());
+Console.WriteLine(charCountPartTwo.Values.Max() - charCountPartTwo.Values.Min());
 
 record AsKey(Pair p, int depth);
 record Rule(Pair p, char res);