Advent-of-Code/2023/1/main.cpp

#include <algorithm>
#include <fstream>
#include <iostream>
#include <map>
#include <set>
#include <sstream>
#include <string>
#include <vector>

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

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

	std::map<std::string, std::string> values =
	{
		{ "0", "0" },
		{ "1", "1" },
		{ "2", "2" },
		{ "3", "3" },
		{ "4", "4" },
		{ "5", "5" },
		{ "6", "6" },
		{ "7", "7" },
		{ "8", "8" },
		{ "9", "9" },
//		{ "zero", 0 },
		{ "one", "1" },
		{ "two", "2" },
		{ "three", "3" },
		{ "four", "4" },
		{ "five", "5" },
		{ "six", "6" },
		{ "seven", "7" },
		{ "eight", "8" },
		{ "nine", "9" }
	};

	auto GetDigit = [&](const std::string &line, int i, bool ascending, std::string &result) {
		std::vector<std::string> tests;
		if(ascending)
		{
			tests.push_back(line.substr(i, 1)); // single digits
			if(i < line.size() - 2)
				tests.push_back(line.substr(i, 3)); // three-letter words
			if(i < line.size() - 3)
				tests.push_back(line.substr(i, 4)); // four-letter words
			if(i < line.size() - 4)
				tests.push_back(line.substr(i, 5)); // five-letter words
		}
		else
		{
			if(i < line.size() - 4)
				tests.push_back(line.substr(i, 5)); // five-letter words
			if(i < line.size() - 3)
				tests.push_back(line.substr(i, 4)); // four-letter words
			if(i < line.size() - 2)
				tests.push_back(line.substr(i, 3)); // three-letter words
			tests.push_back(line.substr(i, 1)); // single digits
		}

		for(auto test : tests)
		{
			if(values.contains(test))
			{
				result = values.at(test);
				return true;
			}
		}

		return false;
	};

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

		std::string first = "";
		std::string last = "";

		// first
		for(auto i = 0; i < line.size(); ++i)
		{
			std::string result;
			if(GetDigit(line, i, true, result))
			{
				first = result;
				break;
			}
		}
		if(first == "")
			std::cerr << "Missing digit in line: " << line << std::endl;

		// last
		for(auto i = 0; i < line.size(); ++i)
		{
			std::string result;
			if(GetDigit(line, line.size() - i - 1, false, result))
			{
				last = result;
				break;
			}
		}
		if(last == "")
			std::cerr << "Missing digit in line: " << line << std::endl;

		std::string val = first + last;
		int val_int = std::atoi(val.c_str());
		std::cout << val_int << std::endl;
		total_pt2 += val_int;
	}

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

	return 0;
}