this post was submitted on 03 Dec 2023
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Advent Of Code

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Day 3: Gear Ratios


Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
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[–] Jummit@lemmy.one 2 points 11 months ago* (last edited 11 months ago)

Input parsing AGAIN?

Lua

-- SPDX-FileCopyrightText: 2023 Jummit
--
-- SPDX-License-Identifier: GPL-3.0-or-later

local lines = {}
for line in io.open("3.input"):lines() do
	table.insert(lines, "."..line..".")
end
local width = #lines[1]
local height = #lines
local function at(x, y, w)
	if y < 1 or y > height then return nil end
	return lines[y]:sub(x, x + w - 1)
end
local sum = 0
local gears = {}
for y, line in ipairs(lines) do
	local start = 1
	local outLine = line
	while true do
		local newStart, numEnd = line:find("%d+", start)
		if not newStart then break end
		local symbol = false
		local num = tonumber(line:sub(newStart, numEnd))
		for y = y - 1, y + 1 do
			local surrounding = at(newStart - 1, y, numEnd - newStart + 3)
			if surrounding then
				if surrounding and surrounding:match("[^.%d]") then
					symbol = true
				end
				for i = 1, #surrounding do
					local gear = surrounding:sub(i, i) == "*"
					if gear then
						if not gears[y] then
							gears[y] = {}
						end
						local x = i + newStart - 2
						if not gears[y][x] then
							gears[y][i + newStart - 2] = {}
						end
						table.insert(gears[y][x], num)
					end
				end
			end
		end
		if symbol then
			sum = sum + num
		end
		start = numEnd + 1
	end
end
print(sum)
local ratio = 0
for _, line in pairs(gears) do
	for _, gears in pairs(line) do
		if #gears == 2 then
			ratio = ratio + gears[1] * gears[2]
		end
	end
end
print(ratio)

Hare (Part one only)

// SPDX-FileCopyrightText: 2023 Jummit
//
// SPDX-License-Identifier: GPL-3.0-or-later

use strings;
use regex;
use fmt;
use os;
use bufio;
use io;
use strconv;
use types;

fn star_in(lines: []str, x: uint, y: uint, w: uint) bool = {
	let start = y;
	if (start > 0) start -= 1;
	let end = y + 1;
	if (end >= len(lines)) end -= 1;
	const re = regex::compile(`[^.0-9]`)!;
	for (let h = start; h <= end; h += 1) {
		fmt::println(strings::sub(lines[h], x, x + w))!;
		if (regex::test(&re, strings::sub(lines[h], x, x + w))) {
			fmt::println("")!;
			return true;
		};
	};
	fmt::println("")!;
	return false;
};

export fn main() void = {
	const file = os::open("3.input")!;
	defer io::close(file)!;
	const buf = bufio::newscanner(file, types::SIZE_MAX);
	let lines: []str = [];
	defer strings::freeall(lines);
	for (true) {
		match (bufio::scan_line(&buf)!) {
		case io::EOF =>
			break;
		case let line: const str =>
			append(lines, strings::dup(line));
		};
	};
	const height = len(lines);
	const width = len(lines[0]);
	let sum: uint = 0;
	let gears: [](uint, uint) = [];
	const num_re = regex::compile(`[0-9]+`)!;
	for (let y = 0u; y < len(lines); y += 1) {
		let nums = regex::findall(&num_re, lines[y]);
		defer regex::result_freeall(nums);
		for (let i = 0z; i < len(nums); i += 1) {
			for (let j = 0z; j < len(nums[i]); j += 1) {
				const find = nums[i][j];
				const num = strconv::stou(find.content)!;
				let start = find.start: uint;
				let w = len(find.content): uint + 2;
				if (start > 0) {
					start -= 1;
				} else {
					w -= 1;
				};
				if (star_in(lines, start, y, w)) {
					sum += num;
				};
			};
		};
	};
	fmt::printfln("{}", sum)!;
};