From 56e890cec0a28c0a485212ccebfaf774235a79a2 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Wed, 3 Jan 2024 23:35:54 +0100
Subject: prepare for more puzzles ... :)

---
 src/day21.cpp | 148 ----------------------------------------------------------
 1 file changed, 148 deletions(-)
 delete mode 100644 src/day21.cpp

(limited to 'src/day21.cpp')

diff --git a/src/day21.cpp b/src/day21.cpp
deleted file mode 100644
index c633155..0000000
--- a/src/day21.cpp
+++ /dev/null
@@ -1,148 +0,0 @@
-#include <cstddef>
-#include <fstream>
-#include <iostream>
-#include <queue>
-#include <set>
-#include <string>
-#include <vector>
-using namespace std;
-
-using position = tuple<size_t, size_t>;
-
-vector<string>
-read_file(string_view filename)
-{
-	fstream        input{ filename };
-	vector<string> data;
-
-	for ( string line; getline(input, line); ) {
-		data.emplace_back(line);
-	}
-
-	return data;
-}
-
-position
-find_start_position(const vector<string>& lines)
-{
-	for ( size_t row = 0; row != lines.size(); ++row ) {
-		for ( size_t col = 0; col != lines[row].size(); ++col ) {
-			if ( lines[row][col] == 'S' ) {
-				return { row, col };
-			}
-		}
-	}
-	return {};
-}
-
-set<position>
-find_neighbours(position pos, const vector<string>& lines)
-{
-	static const vector<position> movements = { { -1, 0 }, { 0, 1 }, { 1, 0 }, { 0, -1 } };
-
-	set<position> neighbours;
-	const auto [row, col] = pos;
-
-	for ( const auto& [drow, dcol]: movements ) {
-		const auto nrow = row + drow;
-		const auto ncol = col + dcol;
-
-		if ( nrow < lines.size() && ncol < lines[0].size() && (lines[nrow][ncol] == '.' || lines[nrow][ncol] == 'S') ) {
-			neighbours.emplace(nrow, ncol);
-		}
-	}
-
-	return neighbours;
-}
-
-size_t
-count(vector<string> lines, position start, size_t rounds)
-{
-	queue<position> positions;
-	positions.emplace(start);
-
-	size_t sum = 0;
-	for ( size_t round = 0; round != rounds; ++round ) {
-		set<position> next_positions;
-
-		sum = 0;
-		while ( !positions.empty() ) {
-			const auto [curr_row, curr_col] = positions.front();
-			lines[curr_row][curr_col]       = '.';
-
-			const auto neighbours = find_neighbours(positions.front(), lines);
-			positions.pop();
-
-			for ( const auto& [row, col]: neighbours ) {
-				lines[row][col] = 'O';
-				next_positions.emplace(row, col);
-				++sum;
-			}
-		}
-
-		for ( const auto& position: next_positions ) {
-			positions.emplace(position);
-		}
-	}
-	return sum;
-}
-
-void
-part1(const vector<string>& lines)
-{
-	const auto start = find_start_position(lines);
-	cout << count(lines, start, 64) << endl;
-}
-
-void
-part2(const vector<string>& lines)
-{
-	const auto start      = find_start_position(lines);
-	const auto [row, col] = start;
-
-	const auto pow2 = [](size_t val) -> size_t {
-		return val * val;
-	};
-
-	const auto   size       = lines.size();
-	const size_t steps      = 26501365;
-	const auto   grid_width = steps / size - 1;
-
-	const auto num_odd_tiles   = pow2(grid_width / 2 * 2 + 1);
-	const auto num_even_tiles  = pow2((grid_width + 1) / 2 * 2);
-	const auto num_odd_points  = count(lines, start, size * 2 + 1);
-	const auto num_even_points = count(lines, start, size * 2);
-
-	auto sum = num_odd_tiles * num_odd_points + num_even_tiles * num_even_points;
-
-	const auto corner_top    = count(lines, { size - 1, col }, size - 1);
-	const auto corner_right  = count(lines, { row, 0 }, size - 1);
-	const auto corner_bottom = count(lines, { 0, col }, size - 1);
-	const auto corner_left   = count(lines, { row, size - 1 }, size - 1);
-
-	sum += corner_top + corner_right + corner_bottom + corner_left;
-
-	const auto small_top_right    = count(lines, { size - 1, 0 }, size / 2 - 1);
-	const auto small_top_left     = count(lines, { size - 1, size - 1 }, size / 2 - 1);
-	const auto small_bottom_right = count(lines, { 0, 0 }, size / 2 - 1);
-	const auto small_bottom_left  = count(lines, { 0, size - 1 }, size / 2 - 1);
-
-	sum += (grid_width + 1) * (small_top_right + small_top_left + small_bottom_right + small_bottom_left);
-
-	const auto large_top_right    = count(lines, { size - 1, 0 }, size * 3 / 2 - 1);
-	const auto large_top_left     = count(lines, { size - 1, size - 1 }, size * 3 / 2 - 1);
-	const auto large_bottom_right = count(lines, { 0, 0 }, size * 3 / 2 - 1);
-	const auto large_bottom_left  = count(lines, { 0, size - 1 }, size * 3 / 2 - 1);
-
-	sum += grid_width * (large_top_right + large_top_left + large_bottom_right + large_bottom_left);
-
-	cout << sum << endl;
-}
-
-int
-main()
-{
-	auto lines = read_file("data/day21.txt");
-	part1(lines);
-	part2(lines);
-}
-- 
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