add solutions for 2015/03

native/solutions/2015/03/common.zig

@@ -0,0 +1,184 @@
+const std = @import("std");
+
+const AnyReader = std.io.AnyReader;
+const Direction = enum { north, south, east, west };
+
+pub const Parser = struct {
+    is_end: bool,
+    is_invalid: bool,
+
+    reader: AnyReader,
+
+    pub fn init(reader: AnyReader) Parser {
+        return .{
+            .is_end = false,
+            .is_invalid = false,
+
+            .reader = reader,
+        };
+    }
+
+    pub fn read(self: *Parser) !Direction {
+        if (self.is_invalid) {
+            return error.InvalidInput;
+        }
+
+        if (self.is_end) {
+            return error.EndOfStream;
+        }
+
+        if (self.reader.readByte()) |byte| {
+            return switch (byte) {
+                '^' => .north,
+                'v' => .south,
+                '>' => .east,
+                '<' => .west,
+                '\n' => self.onEndOfStream(),
+                else => self.onInvalidInput(),
+            };
+        } else |err| {
+            return self.onError(err);
+        }
+    }
+
+    fn onError(self: *Parser, err: anyerror) anyerror!Direction {
+        switch (err) {
+            error.EndOfStream => return self.onEndOfStream(),
+            error.InvalidInput => return self.onInvalidInput(),
+            else => {
+                self.is_end = true;
+                self.is_invalid = true;
+
+                return err;
+            },
+        }
+    }
+
+    fn onEndOfStream(self: *Parser) !Direction {
+        self.is_end = true;
+
+        return error.EndOfStream;
+    }
+
+    fn onInvalidInput(self: *Parser) !Direction {
+        self.is_end = true;
+        self.is_invalid = true;
+
+        return error.InvalidInput;
+    }
+};
+
+pub const Point = struct {
+    x: i32,
+    y: i32,
+
+    pub fn init() Point {
+        return .{
+            .x = 0,
+            .y = 0,
+        };
+    }
+
+    pub fn move(self: *Point, dir: Direction) void {
+        switch (dir) {
+            .north => self.y += 1,
+            .south => self.y -= 1,
+            .east => self.x += 1,
+            .west => self.x -= 1,
+        }
+    }
+};
+
+fn checkInput(comptime input: []const u8, comptime output: []const Direction, is_valid: bool) !void {
+    var stream = std.io.fixedBufferStream(input);
+
+    var parser = Parser.init(stream.reader().any());
+
+    for (output) |expected| {
+        try std.testing.expectEqual(expected, parser.read());
+    }
+
+    const expected_error = if (is_valid) error.EndOfStream else error.InvalidInput;
+
+    try std.testing.expectError(expected_error, parser.read());
+}
+
+fn checkValidInput(comptime input: []const u8, comptime output: []const Direction) !void {
+    try checkInput(input, output, true);
+}
+
+fn checkInvalidInput(comptime input: []const u8, comptime output: []const Direction) !void {
+    try checkInput(input, output, false);
+}
+
+test "parser" {
+    try checkValidInput(
+        "",
+        &.{},
+    );
+
+    try checkValidInput(
+        "\n",
+        &.{},
+    );
+
+    try checkValidInput(
+        "^v><",
+        &.{
+            .north,
+            .south,
+            .east,
+            .west,
+        },
+    );
+
+    try checkValidInput(
+        "^v><\n",
+        &.{
+            .north,
+            .south,
+            .east,
+            .west,
+        },
+    );
+
+    try checkValidInput(
+        "^v><\n^v><",
+        &.{
+            .north,
+            .south,
+            .east,
+            .west,
+        },
+    );
+
+    try checkInvalidInput(
+        "^vV\n",
+        &.{
+            .north,
+            .south,
+        },
+    );
+}
+
+test "point" {
+    var point = Point.init();
+
+    try std.testing.expectEqual(Point{ .x = 0, .y = 0 }, point);
+
+    point.move(.north);
+
+    try std.testing.expectEqual(Point{ .x = 0, .y = 1 }, point);
+
+    point.move(.east);
+
+    try std.testing.expectEqual(Point{ .x = 1, .y = 1 }, point);
+
+    point.move(.south);
+
+    try std.testing.expectEqual(Point{ .x = 1, .y = 0 }, point);
+
+    point.move(.west);
+
+    try std.testing.expectEqual(Point{ .x = 0, .y = 0 }, point);
+}

native/solutions/2015/03/input.fixture

@@ -0,0 +1 @@
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native/solutions/2015/03/part_1.zig

@@ -0,0 +1,43 @@
+const panic = @import("panic");
+const std = @import("std");
+
+const common = @import("./common.zig");
+
+const Allocator = std.mem.Allocator;
+const AnyReader = std.io.AnyReader;
+const Direction = common.Direction;
+const Parser = common.Parser;
+const Point = common.Point;
+
+const Visited = std.hash_map.AutoHashMap(Point, void);
+
+pub fn solve(allocator: Allocator, reader: AnyReader) ![]const u8 {
+    var parser = Parser.init(reader);
+
+    var visited = Visited.init(allocator);
+    defer visited.deinit();
+
+    var santa = Point.init();
+
+    while (parser.read()) |dir| {
+        santa.move(dir);
+
+        try visited.put(santa, undefined);
+    } else |err| {
+        if (err != error.EndOfStream) {
+            return err;
+        }
+    }
+
+    return try std.fmt.allocPrint(allocator, "{d}", .{visited.count()});
+}
+
+test "solution 2015/03/01" {
+    const input_file = @embedFile("./input.fixture");
+    var input = std.io.fixedBufferStream(input_file);
+
+    const answer = try solve(std.testing.allocator, input.reader().any());
+    defer std.testing.allocator.free(answer);
+
+    try std.testing.expectEqualStrings(answer, "2565");
+}

native/solutions/2015/03/part_2.zig

@@ -0,0 +1,54 @@
+const panic = @import("panic");
+const std = @import("std");
+
+const common = @import("./common.zig");
+
+const Allocator = std.mem.Allocator;
+const AnyReader = std.io.AnyReader;
+const Direction = common.Direction;
+const Parser = common.Parser;
+const Point = common.Point;
+
+const Visited = std.hash_map.AutoHashMap(Point, void);
+
+pub fn solve(allocator: Allocator, reader: AnyReader) ![]const u8 {
+    var parser = Parser.init(reader);
+
+    var visited = Visited.init(allocator);
+    defer visited.deinit();
+
+    var is_santa_will_move = true;
+
+    var santa = Point.init();
+    var robo_santa = Point.init();
+
+    while (parser.read()) |dir| {
+        if (is_santa_will_move) {
+            santa.move(dir);
+
+            try visited.put(santa, undefined);
+        } else {
+            robo_santa.move(dir);
+
+            try visited.put(robo_santa, undefined);
+        }
+
+        is_santa_will_move = !is_santa_will_move;
+    } else |err| {
+        if (err != error.EndOfStream) {
+            return err;
+        }
+    }
+
+    return try std.fmt.allocPrint(allocator, "{d}", .{visited.count()});
+}
+
+test "solution 2015/03/02" {
+    const input_file = @embedFile("./input.fixture");
+    var input = std.io.fixedBufferStream(input_file);
+
+    const answer = try solve(std.testing.allocator, input.reader().any());
+    defer std.testing.allocator.free(answer);
+
+    try std.testing.expectEqualStrings(answer, "2639");
+}

native/solutions/registry.zig

@@ -74,6 +74,8 @@ pub const items = [_]Entry{
     entry(.year_2015, .day_01, .part_two, index.solver_2015_01_02),
     entry(.year_2015, .day_02, .part_one, index.solver_2015_02_01),
     entry(.year_2015, .day_02, .part_two, index.solver_2015_02_02),
+    entry(.year_2015, .day_03, .part_one, index.solver_2015_03_01),
+    entry(.year_2015, .day_03, .part_two, index.solver_2015_03_02),
 };
 
 pub fn lookup(year: Year, day: Day, part: Part) ?Solver {

native/solutions/solutions.zig

@@ -2,6 +2,8 @@ pub const solver_2015_01_01 = @import("./2015/01/part_1.zig").solve;
 pub const solver_2015_01_02 = @import("./2015/01/part_2.zig").solve;
 pub const solver_2015_02_01 = @import("./2015/02/part_1.zig").solve;
 pub const solver_2015_02_02 = @import("./2015/02/part_2.zig").solve;
+pub const solver_2015_03_01 = @import("./2015/03/part_1.zig").solve;
+pub const solver_2015_03_02 = @import("./2015/03/part_2.zig").solve;
 
 test {
     @import("std").testing.refAllDecls(@This());