Day 3.1 - first, bad attempt

03/build.zig

@@ -0,0 +1,14 @@
+const Builder = @import("std").build.Builder;
+
+pub fn build(b: *Builder) void {
+    const mode = b.standardReleaseOptions();
+    const exe = b.addExecutable("03", "src/main.zig");
+    exe.setBuildMode(mode);
+    exe.install();
+
+    const run_cmd = exe.run();
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+}

03/input

@@ -0,0 +1,2 @@
+R1004,U520,R137,D262,L403,U857,R50,U679,R788,D98,L717,D1,R367,U608,L125,U703,L562,D701,L718,U357,R742,D860,R557,D117,R950,U546,L506,U836,R951,D460,L38,U893,L1,D217,R262,D950,R239,U384,R971,D289,R323,U878,L525,U687,L831,U523,R94,D33,L879,D318,R633,D775,R879,D351,L120,D8,R31,U49,R328,D598,L380,D160,R261,D716,R459,U533,L444,U412,L326,U93,L193,D621,R236,U769,L319,D885,L559,U509,L62,U321,L667,D505,R556,U159,L5,U126,L262,D946,L168,U491,L56,D831,R926,U926,R562,D270,R785,U436,R852,D629,R872,U716,R549,U435,R462,U191,R318,U91,L637,D682,R647,D53,L789,D725,R312,D366,L287,U29,R85,D657,R88,U300,R795,U378,R800,D391,L594,U791,R205,U352,L510,D975,R47,D311,R319,U579,R214,D112,R996,U874,R328,D578,R37,U689,L543,U16,L580,D230,L714,D58,L580,D658,R218,U535,R149,U996,L173,D316,L90,D372,L364,U700,L60,D70,L250,U276,R580,U505,L682,U943,R336,U847,R810,U963,R874,D740,R732,D328,R926,D447,R638,D102,R696,U211,L594,D354,R384,U81,L884,U916,L168,U759,R631,D702,L598,D382,L647,U642,R537,U53,R897,U954,R263,U445,L41,D91,L51,D338,R219,U269,L689,D172,R627,D287,L440,D504,L253,D252,R815,D108,L282,U835,L243,U638,R910,D306,R755,D202,R69,D862,L537,D947,L180,D835,L111,U832,R939,D449,R180,U105,R892,D837,L153,U215,L695,U957,R923,U496,R608,U739,L711,U700,L838,D117,R479,U852,R795,D955,L386,D70,R728,D40,R580,U777,L877,U284,R414,D300,R105,D372,L317,D91,R653,U920,R956,D496,L543,D363,R374,D283,L696,U466,R467,D878,R660,U590,L962,U619,R991,U848,L648,D191,R459,U125,L998,U19,L214,U947,R188,U103,R916
+L1008,U717,R288,D770,R270,U514,R109,D538,L719,U179,R466,D792,R421,U723,L22,U705,L284,U14,L478,U367,R727,U880,R620,D46,R377,U897,L731,U840,L910,D385,L257,U311,L596,D991,L668,D730,L707,D816,R47,U948,R84,D700,R299,U707,R261,D928,R358,D504,R309,U369,R931,U20,L940,U326,L362,D52,R98,D475,L907,D918,R931,D468,R279,D586,R592,U973,R753,D365,R694,U278,R934,U712,R441,U996,L989,D693,L211,D561,R105,D425,R53,U168,L451,U865,L585,D412,L857,U988,R724,U774,R295,U588,R329,D810,L698,D118,R277,U193,R309,U933,R186,D535,R409,U322,L849,U606,R590,U892,L542,D237,R475,D920,R679,U602,L477,D634,L988,D540,L323,U791,L375,U625,L621,U567,L943,U512,L239,D90,L66,U151,R83,U435,R612,D865,L177,U368,R326,U574,L241,U197,R499,U419,R297,U207,L311,D243,L559,D281,R513,U748,L884,U207,R71,D441,R133,D993,L4,D977,L669,U523,L564,U186,R477,U737,L685,U338,L456,U939,R774,U674,L97,D827,R237,D451,R618,D143,R750,U196,L559,D178,L693,D916,R334,U231,L651,U249,R620,U283,L387,U352,L915,U959,L693,U909,R320,U119,L617,U177,L993,D265,R667,U204,R59,D601,L579,U483,R155,D484,L44,D751,R915,U510,L552,U308,R505,U394,R585,U872,L617,U202,R928,U941,R235,U768,R666,D547,L244,D270,R353,D612,R384,U430,L685,D536,R103,U147,R794,D621,L52,U96,L557,D455,L635,D58,R265,U545,R938,D266,L173,U746,L672,D237,R286,U131,R487,U837,R394,D702,R49,U579,L699,U819,L448,D223,L982,D906,L397,U807,L737,D223,L791,D965,R436,U29,R908,D273,R194,U91,R232,U591,L336,D70,R467,U505,L341,U989,R278,U387,L442,U950,R487,D384,L534,D514,L433,U627,R381,U54,L847,U231,L590

03/src/main.zig

@@ -0,0 +1,213 @@
+const std = @import("std");
+
+const max = 512;
+const xOrigin = max / 2;
+const yOrigin = max / 2;
+
+const Error = error{ParseError};
+
+const State = enum(u8) {
+    Empty,
+    Origin,
+    Line,
+    Intersect,
+};
+
+const Direction = enum(u8) {
+    Up = 'U',
+    Right = 'R',
+    Down = 'D',
+    Left = 'L',
+
+    pub fn parse(in: u8) anyerror!Direction {
+        return switch (in) {
+            'U' => .Up,
+            'R' => .Right,
+            'D' => .Down,
+            'L' => .Left,
+            else => Error.ParseError,
+        };
+    }
+};
+
+const Grid = [max][max]State;
+
+const Step = struct {
+    d: Direction,
+    l: u32,
+
+    pub fn parse(in: []const u8) anyerror!Step {
+        if (in.len < 2) {
+            return error.ParseError;
+        }
+
+        return Step{
+            .d = try Direction.parse(in[0]),
+            .l = try std.fmt.parseInt(u32, in[1..in.len], 10),
+        };
+    }
+};
+
+const World = struct {
+    x: u32,
+    y: u32,
+    grid: *Grid,
+
+    pub fn init(self: *World) void {
+        for (self.grid) |y, y_offset| {
+            for (y) |x, x_offset| {
+                self.grid[y_offset][x_offset] = State.Empty;
+            }
+        }
+    }
+
+    pub fn display(self: *World) void {
+        for (self.grid) |y, y_offset| {
+            for (y) |x, x_offset| {
+                var chr = switch (x) {
+                    State.Empty => " ",
+                    State.Line => ".",
+                    State.Origin => "o",
+                    State.Intersect => "*",
+                };
+
+                std.debug.warn("{}", chr);
+            }
+            std.debug.warn("\n");
+        }
+    }
+
+    pub fn step(self: *World, in: Step, compare: *Grid) void {
+        std.debug.warn("Step: {}\n", in);
+
+        switch (in.d) {
+            .Up => {
+                self.lineY(self.y - in.l, self.y - 1, compare);
+                self.y -= in.l;
+            },
+            .Down => {
+                self.lineY(self.y + 1, self.y + in.l, compare);
+                self.y += in.l;
+            },
+            .Left => {
+                self.lineX(self.x - in.l, self.x - 1, compare);
+                self.x -= in.l;
+            },
+            .Right => {
+                self.lineX(self.x + 1, self.x + in.l, compare);
+                self.x += in.l;
+            },
+        }
+    }
+
+    fn lineX(self: *World, start: u32, end: u32, compare: *Grid) void {
+        var x: u32 = start;
+        while (x <= end) : (x += 1) {
+            self.fill(x, self.y, compare);
+        }
+    }
+
+    fn lineY(self: *World, start: u32, end: u32, compare: *Grid) void {
+        var y: u32 = start;
+        while (y <= end) : (y += 1) {
+            self.fill(self.x, y, compare);
+        }
+    }
+
+    fn fill(self: *World, x: u32, y: u32, compare: *Grid) void {
+        std.debug.warn("\tFilling {},{}\n", x, y);
+
+        var newVal: State = switch (compare[y][x]) {
+            .Line => .Intersect,
+            else => .Line,
+        };
+
+        self.grid[y][x] = newVal;
+    }
+};
+
+fn getLine(stream: *std.fs.File.InStream.Stream) anyerror![]Step {
+    var buf: [10240]u8 = undefined;
+    var out: [1000]Step = undefined;
+    var i: u32 = 0;
+
+    var line = (try stream.readUntilDelimiterOrEof(&buf, '\n')) orelse return Error.ParseError;
+    var iter = std.mem.separate(line, ",");
+
+    while (iter.next()) |value| {
+        std.debug.assert(i < out.len);
+
+        out[i] = try Step.parse(value);
+        i += 1;
+    }
+
+    return out[0..i];
+}
+
+fn manhattan(x: i32, y: i32) u32 {
+    return std.math.absCast(x - xOrigin) + std.math.absCast(y - yOrigin);
+}
+
+pub fn main() anyerror!void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+
+    const alloc = &arena.allocator;
+    const file = std.io.getStdIn();
+    const stream = &file.inStream().stream;
+
+    var grid = try alloc.create(Grid);
+
+    var world: World = World{
+        .x = xOrigin,
+        .y = yOrigin,
+        .grid = grid,
+    };
+
+    world.init();
+    var compare = std.mem.dupe(alloc, Grid, grid);
+
+    // Line 1
+    for (try getLine(stream)) |item| {
+        world.step(item, compare);
+    }
+
+    // reset to origin
+    //std.mem.copy(compare, world.grid);
+    world.x = xOrigin;
+    world.y = yOrigin;
+
+    // Line 2
+    for (try getLine(stream)) |item| {
+        world.step(item, compare);
+    }
+
+    // Ignore the origin
+    world.grid[yOrigin][xOrigin] = State.Origin;
+
+    // detect collisions
+    var minMH: u32 = undefined;
+    var found: bool = false;
+    for (world.grid) |y, yOff| {
+        for (y) |x, xOff| {
+            if (x == State.Intersect) {
+                const mh = manhattan(@intCast(i32, xOff), @intCast(i32, yOff));
+                std.debug.warn("Intersect! {},{} : {}\n", xOff, yOff, mh);
+                if (found) {
+                    if (minMH > mh) {
+                        minMH = mh;
+                    }
+                } else {
+                    found = true;
+                    minMH = mh;
+                }
+            }
+        }
+    }
+
+    if (found) {
+        std.debug.warn("Smallest manhattan: {}\n", minMH);
+    }
+
+    //    world.display();
+}