3 files changed, 606 insertions, 0 deletions

diff --git a/src/day-9/input.txt b/src/day-9/input.txt
new file mode 100644
index 0000000..9c9aa1a
--- /dev/null
+++ b/src/day-9/input.txt
@@ -0,0 +1,496 @@
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diff --git a/src/day-9/part-1.zig b/src/day-9/part-1.zig
new file mode 100644
index 0000000..2f7ea95
--- /dev/null
+++ b/src/day-9/part-1.zig
@@ -0,0 +1,42 @@
+const std = @import("std");
+
+const point = struct { x: i64, y: i64 };
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const alloc = gpa.allocator();
+    
+    const path = "input.txt";
+    const fp = try std.fs.cwd().openFile(path, .{.mode = std.fs.File.OpenMode.read_only});
+    defer fp.close();
+    var reader = fp.reader();
+
+    var buffer: [256]u8 = undefined;
+
+    var points = std.ArrayList(point).init(alloc);
+    defer points.deinit();
+
+    while(try reader.readUntilDelimiterOrEof(&buffer, '\n')) |line| {
+        const i = std.mem.indexOf(u8, line, ",").?;
+
+        const p = point{
+            .x = try std.fmt.parseInt(i64, line[0..i], 10),
+            .y = try std.fmt.parseInt(i64, line[i+1..], 10)
+        };
+
+        try points.append(p);
+    }
+
+    var largest: u64 = 0;
+
+    for(0..points.items.len) |i| {
+        for(i..points.items.len) |z| {
+            if(i == z) continue;
+
+            largest = @max(largest, (1 + @abs(points.items[i].x - points.items[z].x)) * (1 + @abs(points.items[i].y - points.items[z].y)));
+        }
+    }
+
+    std.debug.print("{}\n", .{largest});
+}
diff --git a/src/day-9/part-2.zig b/src/day-9/part-2.zig
new file mode 100644
index 0000000..28898e2
--- /dev/null
+++ b/src/day-9/part-2.zig
@@ -0,0 +1,68 @@
+const std = @import("std");
+
+const point = struct { x: i64, y: i64 };
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const alloc = gpa.allocator();
+    
+    const path = "input.txt";
+    const fp = try std.fs.cwd().openFile(path, .{.mode = std.fs.File.OpenMode.read_only});
+    defer fp.close();
+    var reader = fp.reader();
+
+    var buffer: [256]u8 = undefined;
+
+    var points = std.ArrayList(point).init(alloc);
+    defer points.deinit();
+
+    while(try reader.readUntilDelimiterOrEof(&buffer, '\n')) |line| {
+        const i = std.mem.indexOf(u8, line, ",").?;
+
+        const p = point{
+            .x = try std.fmt.parseInt(i64, line[0..i], 10),
+            .y = try std.fmt.parseInt(i64, line[i+1..], 10)
+        };
+
+        try points.append(p);
+    }
+
+    var largest: u64 = 0;
+
+    for(0..points.items.len) |i| {
+        for(i..points.items.len) |z| {
+            if(i == z) continue;
+
+            const vol = (1 + @abs(points.items[i].x - points.items[z].x)) * (1 + @abs(points.items[i].y - points.items[z].y));
+            if(vol > largest) {
+                const len: i64 = @intCast(@abs(points.items[i].x - points.items[z].x));
+                const high: i64 = @intCast(@abs(points.items[i].y - points.items[z].y));
+
+                const a: i64 = @min(points.items[i].x, points.items[z].x);
+                const b: i64 = a + len;
+                const c: i64 = @min(points.items[i].y, points.items[z].y);
+                const d: i64 = c + high;
+
+                var pass: bool = true;
+                //check if any line intersects with this box, so glad this worked
+                for(0..points.items.len, 1..points.items.len + 1) |o,s| {
+                    const item1 = points.items[o];
+                    const item2 = if(points.items.len > s) points.items[s] else points.items[0];
+                    const verticle = item1.x == item2.x;
+
+                    if(verticle and (a < item1.x and item1.x < b) and !(item1.y >= d and item2.y >= d or item1.y <= c and item2.y <= c)){
+                        pass = false;
+                        break;
+                    } else if(!verticle and (c < item1.y and item1.y < d) and !(item1.x >= b and item2.x >= b or item1.x <= a and item2.x <= a)){
+                        pass = false;
+                        break;
+                    }
+                }
+                if(pass) largest = vol;
+            }
+        }
+    }
+
+    std.debug.print("{}\n", .{largest});
+}