Terribly inefficient. But hey, it works!

day5/data.txt

@@ -0,0 +1,247 @@
+seeds: 487758422 524336848 2531594804 27107767 1343486056 124327551 1117929819 93097070 3305050822 442320425 2324984130 87604424 4216329536 45038934 1482842780 224610898 115202033 371332058 2845474954 192579859
+
+seed-to-soil map:
+152560994 173671324 63296280
+22185606 1527272669 123700133
+1331635416 297391996 25501160
+2532562923 236967604 60424392
+145885739 854580877 6675255
+696074404 427174664 330582271
+0 1407203152 22185606
+1174684019 152310608 21360716
+2679050525 3516671293 482421092
+1227353908 322893156 104281508
+1077860077 757756935 96823942
+3161471617 3999092385 22763615
+1509447184 1650972802 82059456
+4170512486 2802241718 1263617
+1196044735 1495963496 31309173
+1357136576 0 152310608
+4171776103 2679050525 123191193
+1731875772 1733032258 319590386
+282432012 1001625264 405577888
+215857274 1429388758 66574738
+1026656675 2541783913 51203402
+1591506640 861256132 140369132
+688009900 2052622644 8064504
+3457346528 2803505335 713165958
+3184235232 4021856000 273111296
+2051466158 2060687148 481096765
+
+soil-to-fertilizer map:
+2587123207 1612631011 14556918
+425896400 1627187929 180219453
+974395525 3228073255 181091940
+606115853 2482605187 15274968
+621390821 1843957593 329096619
+4269010275 3749182981 25957021
+2601680125 1807407382 36550211
+3749182981 3775140002 91697225
+3337986166 2411426158 71179029
+2306503017 631361705 276943999
+0 205465305 425896400
+950487440 181557220 23908085
+1155487465 1188132368 424498643
+1579986108 2497880155 726516909
+2583447016 3224397064 3676191
+3840880206 3866837227 428130069
+3099614220 2173054212 238371946
+2918057000 0 181557220
+2638230336 908305704 279826664
+
+fertilizer-to-water map:
+0 226390191 111676682
+342717440 10141562 176981703
+3507713259 629378619 187481170
+3695194429 3739990160 60489319
+2747106431 4155961766 11528550
+2120906094 2661985654 77106422
+3983043532 1233406588 239832885
+3045388563 4287081612 7885684
+529840705 187123265 39266926
+2198012516 1102191084 16615097
+3053274247 4167490316 104130064
+2564366436 2756374717 129809025
+3331241613 816859789 87383675
+3418625288 3536806097 36187146
+1239632010 3393454292 143351805
+1147966039 1776147938 91665971
+1382983815 2230578660 82475007
+4222876417 1045170068 57021016
+3455914127 2313053667 4640764
+2835800762 3800479479 42590884
+4279897433 1473239473 15069863
+3780709534 2342720217 202333998
+1753297424 3902953503 253008263
+1465458822 1488309336 287838602
+3454812434 2588893134 1101693
+3287402694 2545054215 43838919
+2704024450 1002088087 43081981
+629378619 2589994827 71990827
+3189558071 904243464 97844623
+2214627613 2886183742 264407413
+2006305687 1118806181 114600407
+3460554891 1867813909 47158368
+3755683748 2317694431 25025786
+111676682 338066873 231040758
+519699143 0 10141562
+2479035026 3313735125 69870178
+2548905204 4271620380 15461232
+2775917622 3843070363 59883140
+3157404311 2198424900 32153760
+864513416 1914972277 283452623
+2758634981 2739092076 17282641
+701369446 3150591155 163143970
+2878391646 3572993243 166996917
+2694175461 3383605303 9848989
+
+water-to-light map:
+1222332482 2306154207 322881400
+3721269109 3329751112 30895612
+4157109606 3191893422 137857690
+2602036554 3676681423 255279159
+2293973174 3078247260 113646162
+1208052724 2246358310 14279758
+1835200232 1597610395 302070784
+3118371905 1208052724 389557671
+2137271016 3519979265 156702158
+2501933666 1952285487 54586749
+3753874345 1899681179 52604308
+3806478653 3931960582 7636192
+3973340148 2006872236 24436917
+3814114845 2629035607 159225303
+3507929576 2031309153 213339533
+3752164721 2244648686 1709624
+2857315713 3939596774 261056192
+3997777065 3360646724 159332541
+2556520415 2260638068 45516139
+2407619336 4200652966 94314330
+1545213882 2788260910 289986350
+
+light-to-temperature map:
+40645637 589707204 89929230
+2331703372 3634092968 247989827
+375013050 880330876 388603146
+959059361 861524497 18806379
+3081535248 2703807387 671456921
+2080450790 1678532701 100545991
+1520717011 1522300302 156232399
+3801827392 4285326304 9640992
+2834731556 1990942492 115059472
+2949791028 2566169187 71005535
+3020796563 4224587619 60738685
+4159346802 1855321998 135620494
+977865740 0 297257755
+3811468384 3375264308 157802817
+2304295289 1779078692 27408083
+3752992169 1806486775 48835223
+2579693199 3882082795 255038357
+130574867 328095764 236983298
+4081903724 3533067125 77443078
+367558165 310812857 7454885
+3969271201 3610510203 23582765
+4080320433 1520717011 1583291
+777171298 679636434 181888063
+2180996781 2106001964 56665843
+3992853966 4137121152 87466467
+0 1268934022 6189473
+30817615 318267742 9828022
+1676949410 2162667807 403501380
+763616196 297257755 13555102
+6189473 565079062 24628142
+2237662624 2637174722 66632665
+
+temperature-to-humidity map:
+3854764317 3086190444 332386294
+2110554705 1096342109 65650849
+3236082645 1211923153 20175736
+846106827 1853452836 60731419
+596073066 1972015961 100470927
+1202254149 2647779239 280062599
+2176205554 2107199879 422980149
+2943801812 432921932 58618218
+1824616452 1161992958 3317671
+1201112206 2106057936 1141943
+1840640266 1631373972 178403432
+2767591984 62542954 155027747
+2743880612 491540150 8409669
+62542954 1273100182 24571446
+4208015516 3772661112 86951780
+3477752908 217570701 215351231
+2019043698 3681150105 91511007
+1482316748 4027597725 172205397
+766244356 4199803122 79862471
+950513678 665972626 23438579
+89279871 1232098889 41001293
+1654522145 1914184255 36130017
+3002420030 3660808941 20341164
+452765307 1525178112 98766078
+551531385 840194947 44541681
+1827934123 2072486888 12706143
+87114400 3859612892 2165471
+1091551468 3873351076 109560738
+2714852730 884736628 29027882
+906838246 1809777404 43675432
+760232399 1297671628 6011957
+696543993 3861778363 11572713
+3693104139 633914109 32058517
+1690652162 499949819 133964290
+151982853 3418576738 142433848
+2922619731 689411205 21182081
+2599185703 1165310629 46612524
+2752290281 4279665593 15301703
+3022761194 913764510 182577599
+2645798227 3561010586 69054503
+130281164 1950314272 21701689
+973952257 2530180028 117599211
+715546488 3982911814 44685911
+4187150611 2085193031 20864905
+3256258381 1303683585 221494527
+3725162656 710593286 129601661
+708116706 1623944190 7429782
+3205338793 3630065089 30743852
+294416701 2927841838 158348606
+
+humidity-to-location map:
+3745579304 2724582328 81388084
+2201043082 981698567 150857305
+456470998 689872919 41258774
+2351900387 2312761976 47825019
+497729772 314502888 115122928
+4036836228 4279991461 14975835
+784121118 3255986437 5687937
+612852700 0 118278993
+3894168411 842107405 27168107
+3127730376 4061803810 218187651
+1230572305 1958697503 125808488
+304425981 163566931 106757079
+789809055 3790646012 241507252
+1777374448 1871672054 39148062
+1816522510 1504159194 367512860
+235721965 621168903 68704016
+4051812063 1480547431 14406303
+3826967388 1228960483 58471320
+411183060 118278993 45287938
+3921336518 869275512 103693352
+4025029870 2304659906 8102070
+2838210137 1132555872 96404611
+2934614748 1287431803 193115628
+1414367080 3422182046 363007368
+3345918027 1494953734 9205460
+2184035370 2805970412 17007712
+2631131158 2088210279 207078979
+1356380793 784121118 57986287
+2399725406 2493176576 231405752
+1031316307 3261674374 160507672
+44178878 429625816 191543087
+4195166765 3165556554 90429883
+4285596648 2295289258 9370648
+3403000874 2822978124 342578430
+1191823979 3785189414 5456598
+1197280577 2459884848 33291728
+4066218366 4032153264 29650546
+3355123487 1910820116 47877387
+3885438708 972968864 8729703
+0 270324010 44178878
+4095868912 2360586995 99297853
+4033131940 2084505991 3704288

day5/main.zig

@@ -0,0 +1,141 @@
+const std = @import("std");
+
+const Range = struct { destination: u64, source: u64, length: u64 };
+const Map = struct { from: []const u8, to: []const u8, ranges: std.ArrayList(Range) };
+
+pub fn main() !void {
+    const content = @embedFile("data.txt");
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const allocator = gpa.allocator();
+
+    // split the file content on empty lines
+    var sections = std.mem.split(u8, content, "\n\n");
+
+    // parse out the first line, collecting seeds into an ArrayList
+    var seedSection = std.mem.split(u8, sections.next().?, " ");
+    var seeds = std.ArrayList(u64).init(allocator);
+    defer seeds.deinit();
+    _ = seedSection.next();
+    while (seedSection.next()) |s| {
+        try seeds.append(try std.fmt.parseInt(u64, s, 10));
+    }
+
+    var maps = std.ArrayList(Map).init(allocator);
+    defer maps.deinit();
+
+    // iterate over each section, parse into Map structs, append them onto the maps ArrayList
+    while (sections.next()) |s| {
+        var lines = std.mem.split(u8, s, "\n");
+        var firstLine = lines.next().?;
+        var words = std.mem.split(u8, firstLine, " ");
+        // grab the first "word" of the first line, and split it on -
+        var parts = std.mem.split(u8, words.next().?, "-");
+        const from = parts.next().?;
+        _ = parts.next();
+        const to = parts.next().?;
+
+        var ranges = std.ArrayList(Range).init(allocator);
+        // TODO: do I need to deinit ranges... somewhere?
+        while (lines.next()) |line| {
+            if (line.len == 0) {
+                continue;
+            }
+            var nums = std.mem.split(u8, line, " ");
+            var destination = try std.fmt.parseInt(u64, nums.next().?, 10);
+            var source = try std.fmt.parseInt(u64, nums.next().?, 10);
+            var length = try std.fmt.parseInt(u64, nums.next().?, 10);
+            const range = Range{ .destination = destination, .source = source, .length = length };
+            try ranges.append(range);
+        }
+        const map = Map{ .from = from, .to = to, .ranges = ranges };
+        try maps.append(map);
+    }
+
+    var lowestLocation: ?u64 = null;
+    for (seeds.items) |seed| {
+        // loop starting from the "seed" map until we have a location
+        var from: []const u8 = "seed";
+        var val = seed;
+
+        while (!std.mem.eql(u8, from, "location")) {
+            const map = findMap(from, maps).?;
+            val = findNewValue(val, map);
+            from = map.to;
+        }
+        if (lowestLocation) |l| {
+            if (val < l) {
+                lowestLocation = val;
+            }
+        } else {
+            lowestLocation = val;
+        }
+    }
+
+    std.debug.print("Part 1 {?d}\n", .{lowestLocation});
+
+    // Part 2
+    // Can we go backwards?
+    var i: u64 = 0;
+    outer: while (true) {
+        var to: []const u8 = "location";
+        var val = i;
+
+        while (!std.mem.eql(u8, to, "seed")) {
+            const map = findMapReverse(to, maps).?;
+            val = findNewValueReverse(val, map);
+            to = map.from;
+        }
+
+        var idx: u8 = 0;
+        while (idx < seeds.items.len) : (idx += 2) {
+            const lower = seeds.items[idx];
+            const upper = lower + seeds.items[idx + 1];
+            if (val >= lower and val < upper) {
+                break :outer;
+            }
+        }
+        i += 1;
+    }
+
+    std.debug.print("Part 2 {?d}\n", .{i});
+}
+
+// given the "from" type, find the map that we should follow
+fn findMap(from: []const u8, maps: std.ArrayList(Map)) ?Map {
+    for (maps.items) |map| {
+        if (std.mem.eql(u8, map.from, from)) {
+            return map;
+        }
+    }
+    return null;
+}
+
+fn findNewValue(val: u64, map: Map) u64 {
+    for (map.ranges.items) |r| {
+        if (val >= r.source and val < r.source + r.length) {
+            return r.destination + val - r.source;
+        }
+    }
+    // if no range fits, return the original value
+    return val;
+}
+
+// given the "to" type, find the map that we should follow
+fn findMapReverse(to: []const u8, maps: std.ArrayList(Map)) ?Map {
+    for (maps.items) |map| {
+        if (std.mem.eql(u8, map.to, to)) {
+            return map;
+        }
+    }
+    return null;
+}
+
+fn findNewValueReverse(val: u64, map: Map) u64 {
+    for (map.ranges.items) |r| {
+        if (val >= r.destination and val < r.destination + r.length) {
+            return r.source + val - r.destination;
+        }
+    }
+    // if no range fits, return the original value
+    return val;
+}

day5/test.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