Advent of code 2021 - day 2 - solution

advent-of-code-2021-day2.cpp

#include <iostream>
#include <cmath>
#include <map>
#include <boost/algorithm/string.hpp>
#include <boost/format.hpp>
#include <day2.hpp>

namespace day2
{
    std::string solution_part1(std::istream &std_input)
    {
        std::string line;
        std::vector<std::string> commandLine;
        std::map<std::string, int> commands;

        commands["forward"] = 0;
        commands["down"] = 0;
        commands["up"] = 0;

        while (std::getline(std_input, line))
        {
            boost::split(commandLine, line, boost::algorithm::is_space());
            commands[commandLine[0]] += std::stoi(commandLine[1]);
        }

        return std::to_string(commands["forward"] * std::abs(commands["down"] - commands["up"]));
    }

    std::string solution_part2(std::istream &std_input)
    {
        std::string line;
        std::vector<std::string> commandLine;

        int horizontal = 0, aim = 0, depth = 0;
        int value;
        std::string move;

        while (std::getline(std_input, line))
        {
            boost::split(commandLine, line, boost::algorithm::is_space());
            move = commandLine[0];
            value = std::stoi(commandLine[1]);

            if (move == "up")
            {
                aim -= value;
            }
            else if (move == "down")
            {
                aim += value;
            }
            else if (move == "forward")
            {
                horizontal += value;
                depth += aim * value;
            }
        }

        return std::to_string(depth * horizontal);
    }
}