day4.cpp

#include "TextUtils.hpp"

#include <cmath>
#include <map>

int solve(const std::string& line)
{
	auto split_line      = TextUtils::Split(line, ":|");
	auto winning_numbers = TextUtils::Split(split_line[1], " ");
	auto my_numbers      = TextUtils::Split(split_line[2], " ");

	int exponent = 0;

	for (auto winning_number : winning_numbers)
	{
		for (auto my_number : my_numbers)
		{
			if (my_number != "" && winning_number != "" && my_number == winning_number)
			{
				exponent += 1;
			}
		}
	}

	return exponent;
}

int main(int p_argv, char** p_argc)
{
	std::fstream input_file;
	input_file.open("input_day4.txt", std::ios::in);

	std::cout << std::boolalpha;
	std::cout << "Day 4, lets go!" << std::endl;

	std::string line;

	int resultPart1 = 0;
	int resultPart2 = 0;
	int line_index  = 0;

	std::map<int, int> numberOfCopies;
	while (std::getline(input_file, line))
	{
		int match = solve(line);

		resultPart1 += (match > 0) ? pow(2, match - 1) : 0;

		numberOfCopies[line_index] += 1;
		resultPart2 += numberOfCopies[line_index];

		for (int i = line_index + 1; i <= line_index + match; i++)
		{
			numberOfCopies[i] += numberOfCopies[line_index];
		}

		line_index++;
	}

	std::cout << "Part 1: " << resultPart1 << std::endl;
	std::cout << "Part 2: " << resultPart2 << std::endl;
}