From 7f3712b1a2f716a038105a5c6f29a093fc20d4df Mon Sep 17 00:00:00 2001
From: Polesznyák Márk <contact@pml68.dev>
Date: Thu, 4 Dec 2025 16:36:34 +0100
Subject: feat: day4 part2 complete

---
 day4/part2/main.ha | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 day4/part2/main.ha

(limited to 'day4/part2')

diff --git a/day4/part2/main.ha b/day4/part2/main.ha
new file mode 100644
index 0000000..5e1d10a
--- /dev/null
+++ b/day4/part2/main.ha
@@ -0,0 +1,70 @@
+use fmt;
+use io;
+use os;
+use strconv;
+use strings::{fromutf8_unsafe, split, torunes};
+
+const adjacent_positions: [8][2]int = [
+	[-1, -1],
+	[ 0, -1],
+	[ 1, -1],
+	[-1,  0],
+	[ 1,  0],
+	[-1,  1],
+	[ 0,  1],
+	[ 1,  1]
+];
+
+fn adjacent_rolls(grid: [][]rune, x: int, y: int) u64 = {
+	let rolls: u64 = 0;
+
+	for (let pos .. adjacent_positions) {
+		let col = x: int + pos[0];
+		let row = y: int + pos[1];
+
+		if (col < 0 || col >= len(grid[0]): int ||
+			row < 0 || row >= len(grid): int)
+			continue;
+
+
+		if (grid[row][col] == '@')
+			rolls += 1;
+	};
+
+	return rolls;
+};
+
+export fn main() void = {
+	let handle = os::open("input.txt")!;
+	defer io::close(handle)!;
+
+	let buf = io::drain(handle)!;
+	defer free(buf);
+
+	let lines = split(fromutf8_unsafe(buf), "\n")!;
+	let grid: [][]rune = [];
+
+	let total_removable_rolls: u64 = 0;
+	let removed_rolls: u64 = 666;
+
+	for (let line .. lines) {
+		if (line != "")
+			append(grid, torunes(line)!)!;
+	};
+
+	for (removed_rolls > 0) {
+		removed_rolls = 0;
+		for (let x: size = 0; x < len(grid[0]); x += 1) {
+			for (let y: size = 0; y < len(grid); y += 1) {
+				if (grid[y][x] == '@' &&
+					adjacent_rolls(grid, x: int, y: int) < 4) {
+					grid[y][x] = '.';
+					total_removable_rolls += 1;
+					removed_rolls += 1;
+				};
+			};
+		};
+	};
+
+	fmt::printfln("Answer: {}", total_removable_rolls)!;
+};
-- 
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