Finish day09, part 1

src/days/day09.zig

@@ -1,7 +1,91 @@
 const std = @import("std");
 
-pub const title = "Day 09";
+pub const title = "Day 09: Movie Theater";
 
-pub fn run(_: std.mem.Allocator) !void {
+pub fn run(allocator: std.mem.Allocator) !void {
+    const input = @embedFile("./input/day09.txt");
+    //const input =
+    //    \\7,1
+    //    \\11,1
+    //    \\11,7
+    //    \\9,7
+    //    \\9,5
+    //    \\2,5
+    //    \\2,3
+    //    \\7,3
+    //    ;
+
+    var lines = std.mem.tokenizeScalar(u8, input, '\n');
+
+    var tiles: std.ArrayList(Tile) = .empty;
+    defer tiles.deinit(allocator);
+
+    while (lines.next()) |line| {
+        var coordinates = std.mem.tokenizeScalar(u8, line, ',');
+        const x = blk: {
+            const s = coordinates.next() orelse continue;
+            break :blk try std.fmt.parseUnsigned(u64, s, 10);
+        };
+        const y = blk: {
+            const s = coordinates.next() orelse continue;
+            break :blk try std.fmt.parseUnsigned(u64, s, 10);
+        };
+        try tiles.append(allocator, .{ .x = x, .y = y });
+    }
+
+    var largest_area: usize = 0;
+    var largest_rectangle: Rectangle = undefined;
+    for (tiles.items, 0..) |first_tile, i| {
+        for (tiles.items[i + 1..]) |second_tile| {
+            const rectangle = first_tile.rectangle(second_tile);
+            const area = rectangle.area();
+            if (area > largest_area) {
+                largest_area = area;
+                largest_rectangle = rectangle;
+            }
+        }
+    }
+
+    std.debug.print("rectangle = {f}\n", .{largest_rectangle});
+
+    var buffer: [64]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&buffer);
+    const stdout = &stdout_writer.interface;
+
+    try stdout.print("{d}\n", .{largest_area});
+
+    try stdout.flush();
 }
 
+const Tile = struct {
+    x: u64,
+    y: u64,
+
+    const Self = @This();
+
+    pub fn format(self: Self, w: *std.io.Writer) std.io.Writer.Error!void {
+        try w.print("{d},{d}", .{self.x, self.y});
+    }
+
+    pub fn rectangle(self: Self, other_corner: Self) Rectangle {
+        return .{ .a = self, .b = other_corner };
+    }
+};
+
+const Rectangle = struct {
+    a: Tile,
+    b: Tile,
+
+    const Self = @This();
+
+    pub fn format(self: Self, w: *std.io.Writer) std.io.Writer.Error!void {
+        try w.print("{f} to {f}", .{self.a, self.b});
+    }
+
+    pub fn area(self: Self) u64 {
+        const width = @max(self.a.x, self.b.x) - @min(self.a.x, self.b.x) + 1;
+        const height = @max(self.a.y, self.b.y) - @min(self.a.y, self.b.y) + 1;
+        return width * height;
+    }
+};
+