aocpp/2019/08.cpp

#include <algorithm>
#include <cstdint>
#include <array>
#include <iostream>
#include <iterator>
#include <vector>
#include <string_view>
#include <numeric>

#include <aocpp/Startup.hpp>

namespace {

auto Part1(std::string const& line) {
  std::size_t part1 = 0;
  auto seen = std::numeric_limits<std::size_t>::max();
  for (auto it = line.begin();
       std::distance(it, line.end()) >= 150;
       std::advance(it, 150))
  {
    auto zeros = std::size_t(std::count(it, it + 150, '0'));
    if (zeros < seen) {
      seen = zeros;
      part1
        = std::count(it, it + 150, '1')
        * std::count(it, it + 150, '2');
    }
  }
  return part1;
}

auto Flatten(std::string const& line) {
  std::string merged(150, ' ');
  for (std::size_t i = 0; i < 150; i++) {
    for (auto it = line.begin();
         std::distance(it, line.end()) >= 150;
         std::advance(it, 150))
    {
      if ('2' != it[i]) {
        merged[i] = it[i];
        break;
      }
    }
  }
  return merged;
}

auto Draw(std::ostream & out, std::string const& picture) {
  for (std::size_t y = 0; y < 6; y++) {
    for (std::size_t x = 0; x < 25; x++) {
      out << ('1' == picture[y*25+x] ? "▓" : "░");
    }
    out << std::endl;
  }
}

} // namespace

auto Main(std::istream & in, std::ostream & out) -> void
{
  std::string line;
  std::getline(in, line);
  out << "Part 1: " << Part1(line) << std::endl;
  Draw(out, Flatten(line));
}