Advent-of-Code/2022/8/main.cpp

#include <fstream>
#include <iostream>
#include <set>
#include <string>
#include <vector>

int main()
{
	std::ifstream ifs("data.txt");
	if(!ifs.is_open())
	{
		std::cerr << "Missing data.txt." << std::endl;
		return -1;
	}

	unsigned long total = 0;
	unsigned long total_pt2 = 0;

	std::vector<std::vector<int>> trees;

	// Parse:
	for(std::string line; std::getline(ifs, line); )
	{
		if(line == "")
			continue;

		trees.push_back({});
		for(const char &ch : line)
			trees.back().push_back(ch - '0');
	}

	std::set<std::pair<int, int>> visible_coordinates;
	for(auto y = 0; y < trees.size(); ++y)
	{
		visible_coordinates.insert({0,y});
		visible_coordinates.insert({trees[y].size()-1,y});
	}
	for(auto x = 1; x < trees[0].size() - 1; ++x)
	{
		visible_coordinates.insert({x,0});
		visible_coordinates.insert({x,trees.size()-1});
	}

	// left to right, right to left IN EACH ROW:
	std::vector<int> points;
	for(auto y = 1; y < trees.size() - 1; ++y)
	{
		points.clear();

		// initialize list with the first value
		points.push_back(trees[y][0]);

		// iterate through the rest:
		for(auto x = 1; x < trees[y].size(); ++x)
		{
			// if it's higher than the most recent one:
			const auto val = trees[y][x];
			if(val > points.back())
			{
				points.push_back(val);
				visible_coordinates.insert({x,y});
			}
		}
	}
	for(auto y = 1; y < trees.size() - 1; ++y)
	{
		points.clear();

		// initialize list with the first value
		points.push_back(trees[y][trees.size()-1]);

		// iterate through the rest:
		for(auto x = trees[y].size() - 2; x > 0; --x)
		{
			// if it's higher than the most recent one:
			const auto val = trees[y][x];
			if(val > points.back())
			{
				points.push_back(val);
				visible_coordinates.insert({x,y});
			}
		}
	}
	for(auto x = 1; x < trees[0].size() - 1; ++x)
	{
		points.clear();

		// initialize list with the first value
		points.push_back(trees[0][x]);

		// iterate through the rest:
		for(auto y = 1; y < trees.size(); ++y)
		{
			// if it's higher than the most recent one:
			const auto val = trees[y][x];
			if(val > points.back())
			{
				points.push_back(val);
				visible_coordinates.insert({x,y});
			}
		}
	}
	for(auto x = 1; x < trees[0].size() - 1; ++x)
	{
		points.clear();

		// initialize list with the first value
		points.push_back(trees[trees.size()-1][x]);

		// iterate through the rest:
		for(auto y = trees.size()-2; y > 0; --y)
		{
			// if it's higher than the most recent one:
			const auto val = trees[y][x];
			if(val > points.back())
			{
				points.push_back(val);
				visible_coordinates.insert({x,y});
			}
		}
	}

	total += visible_coordinates.size();

	for(auto y = 0; y < trees.size(); ++y)
	{
		for(auto x = 0; x < trees[y].size(); ++x)
		{
			if(visible_coordinates.contains({x,y}))
				std::cout << "\033[1;31m";
			else
				std::cout << "\033[0m";
			std::cout << trees[y][x];
		}
		std::cout << std::endl;
	}
	std::cout << "\033[0m";

	std::cout << "    Total: " <<     total << std::endl;
	std::cout << "PT2 Total: " << total_pt2 << std::endl;

	return 0;
}