Day 5

I...I know there's a way to map all the ranges together to build intersections and make a smart decision about this, but I just...don't really want to do that. This brute force approach finishes in about 55 seconds in Debug and 5 seconds in Release on my PC in a single thread, which...is fine. For now.

advent-of-code-2023.csproj

@@ -38,6 +38,8 @@
 	  <EmbeddedResource Include="inputs\03a.txt" />
 	  <EmbeddedResource Include="inputs\04.txt" />
 	  <EmbeddedResource Include="inputs\04a.txt" />
+	  <EmbeddedResource Include="inputs\05.txt" />
+	  <EmbeddedResource Include="inputs\05a.txt" />
 	</ItemGroup>
 
 	<ItemGroup>

inputs/05.txt

@@ -0,0 +1,190 @@
+seeds: 1636419363 608824189 3409451394 227471750 12950548 91466703 1003260108 224873703 440703838 191248477 634347552 275264505 3673953799 67839674 2442763622 237071609 3766524590 426344831 1433781343 153722422
+
+seed-to-soil map:
+2067746708 2321931404 124423068
+2774831547 3357841131 95865403
+3776553292 3323317283 34523848
+4167907733 3453706534 116376261
+1190847573 767701596 554806188
+2870696950 1975607604 173919437
+1980384731 2612856575 87361977
+3380570559 2987564153 335753130
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+4077167815 3804196813 90739918
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+4064098137 3894936731 13069678
+4284283994 2700218552 10683302
+2468832075 2472320405 59919536
+3716323689 3570082795 60229603
+1085396685 662250708 105450888
+1030174777 1322507784 22912174
+1975607604 2446354472 4777127
+3828940251 2532239941 80616634
+584992388 1930412346 7315040
+592307428 0 437867349
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+0 1345419958 584992388
+2192169776 2710901854 276662299
+2600947132 3630312398 173884415
+1053086951 1937727386 32309734
+3065805193 3908006409 314765366
+
+soil-to-fertilizer map:
+4148533839 3658735071 146433457
+656556737 471425735 68165409
+751630557 539591144 462446129
+724722146 1002037273 26908411
+0 24799538 226917727
+4049709448 3143711443 98824391
+412048729 251717265 219708470
+3321838617 2645077606 72145759
+3869354568 2464722726 180354880
+2044900648 1380852911 42721698
+226917727 1028945684 185131002
+3111204505 2717223365 210634112
+2129227343 1423574609 981977162
+1380852911 2927857477 215853966
+3393984376 2405551771 59170955
+3453155331 3242535834 416199237
+1596706877 3805168528 448193771
+2087622346 4253362299 41604997
+631757199 0 24799538
+
+fertilizer-to-water map:
+2679101382 2898500255 208361454
+3672966601 3700867560 107718031
+1764241275 4242224976 41519499
+1018987051 346629037 49456831
+518817716 396085868 3722249
+1224466235 306138732 40490305
+1068679130 947256497 122607155
+1328820253 625833852 156797976
+222363356 782631828 128136603
+4106081288 2497628211 144953761
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+2177283137 3415053348 9638645
+1485618229 910768431 36488066
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+482104460 0 36713256
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+118194361 213050410 93088322
+1869091498 3106861709 308191639
+1068443882 399808117 235248
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+0 94856049 118194361
+
+water-to-light map:
+487890089 1253174910 48217379
+1162866447 2295971038 331509140
+3115016077 4085918002 209049294
+3600618057 2743705059 694349239
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+536107468 1846205805 344964913
+0 2627480178 78943404
+
+light-to-temperature map:
+2934276762 3692860946 134937994
+2222730788 3468116804 32924074
+2030910720 3501040878 191820068
+2876227610 3450265581 17851223
+2821863146 1926340324 54364464
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+950380331 232213448 1080530389
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+3682811243 47027822 185185626
+2255654862 0 47027822
+2420383955 1980704788 401479191
+
+temperature-to-humidity map:
+3474899002 2152529659 335631613
+1227362297 2657517973 1047434675
+1147289328 4214894327 80072969
+3069802422 3704952648 405096580
+4233143053 2090705416 61824243
+3979887316 1837449679 253255737
+3810530615 2488161272 169356701
+1042444229 4110049228 104845099
+2274796972 1042444229 718141444
+2992938416 1760585673 76864006
+
+humidity-to-location map:
+2905941546 1669212802 106379169
+3490393041 2571512629 24111360
+3327134512 896350741 163258529
+163044169 321738120 136537257
+1794114599 1475899779 31051829
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+1254184202 1194301285 19606964
+1486504318 1775591971 115009557

inputs/05a.txt

@@ -0,0 +1,33 @@
+seeds: 79 14 55 13
+
+seed-to-soil map:
+50 98 2
+52 50 48
+
+soil-to-fertilizer map:
+0 15 37
+37 52 2
+39 0 15
+
+fertilizer-to-water map:
+49 53 8
+0 11 42
+42 0 7
+57 7 4
+
+water-to-light map:
+88 18 7
+18 25 70
+
+light-to-temperature map:
+45 77 23
+81 45 19
+68 64 13
+
+temperature-to-humidity map:
+0 69 1
+1 0 69
+
+humidity-to-location map:
+60 56 37
+56 93 4

src/05.cs

@@ -0,0 +1,136 @@
+namespace aoc2023;
+
+internal class Day05 : Day
+{
+    record map(long destStart, long sourceStart, long len)
+    {
+        public long Translate(long input)
+        {
+            if (input >= sourceStart && input < sourceStart + len)
+            {
+                var offset = input - sourceStart;
+                return destStart + offset;
+            }
+
+            return input;
+        }
+
+        public long ReverseTranslate(long input)
+        {
+            if (input >= destStart && input < destStart + len)
+            {
+                var offset = input - destStart;
+                return sourceStart + offset;
+            }
+
+            return input;
+        }
+    }
+
+    private long TranslateInMapSet(List<map> set, long input)
+    {
+        foreach (var m in set)
+        {
+            var translated = m.Translate(input);
+            if (translated != input)
+            {
+                return translated;
+            }
+        }
+
+        return input;
+    }
+
+    private long ReverseTranslateInMapSet(List<map> set, long input)
+    {
+        foreach (var m in set)
+        {
+            var translated = m.ReverseTranslate(input);
+            if (translated != input)
+            {
+                return translated;
+            }
+        }
+
+        return input;
+    }
+
+    private List<long> seeds = new();
+    private List<List<map>> maps = new();
+    internal override void Parse()
+    {
+        var lines = Util.Parsing.ReadAllLines($"{GetDay()}");
+        int mapNum = -1;
+        foreach (var line in lines)
+        {
+            if (seeds.Count == 0)
+            {
+                var split = line.Split(": ");
+                seeds.AddRange(split[1].Split(' ').Select(long.Parse));
+                continue;
+            }
+            if (string.IsNullOrWhiteSpace(line))
+            {
+                mapNum++;
+                continue;
+            }
+
+            if (line.Contains(':'))
+            {
+                maps.Add(new());
+                continue;
+            }
+
+            var nums = line.Split(' ').Select(long.Parse).ToArray();
+            maps[mapNum].Add(new(nums[0], nums[1], nums[2]));
+        }
+    }
+
+    internal override string Part1()
+    {
+        long lowest = long.MaxValue;
+        foreach (var seed in seeds)
+        {
+            long curr = seed;
+            foreach (var set in maps)
+            {
+                curr = TranslateInMapSet(set, curr);
+            }
+
+            if (curr < lowest)
+            {
+                lowest = curr;
+            }
+        }
+
+        return $"Lowest location number: <+white>{lowest}";
+    }
+
+    internal override string Part2()
+    {
+        List<(long start, long len)> seedranges = new();
+        for (int i = 0; i < seeds.Count; i += 2)
+        {
+            seedranges.Add((seeds[i], seeds[i+1]));
+        }
+
+        for (long i = 0; i < long.MaxValue; i++)
+        {
+            long pos = i;
+            for (int j = maps.Count - 1; j >= 0; j--)
+            {
+                pos = ReverseTranslateInMapSet(maps[j], pos);
+            }
+
+            foreach (var range in seedranges)
+            {
+                if (pos >= range.start && pos < range.start + range.len)
+                {
+                    return $"Lowest location number in seed ranges is at seed {pos}: <+white>{i}";
+                }
+            }
+        }
+
+        throw new Exception("didn't find it...");
+    }
+}