aocpp/2017/13.cpp

#include <cstdint>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <tuple>

#include <doctest.h>

#include <aocpp/Startup.hpp>

namespace {

struct Scanner {
  std::uint64_t depth, range, position, length;
};

auto Parse(std::istream & in)
-> std::vector<Scanner>
{
  std::uint64_t depth, range;
  char skip;
  std::vector<Scanner> result;
  while (in >> depth >> skip >> range) {
    auto len = range*2-2;
    result.push_back(Scanner{depth, range, depth%len, len});
  }
  return result;
}

auto Caught(std::vector<Scanner> const& scanners) -> std::size_t {
  std::uint64_t severity = 0;
  for (auto const& scanner : scanners) {
    if (scanner.position == 0) {
      severity += scanner.depth * scanner.range;
    }
  }
  return severity;
}

auto Delay(std::vector<Scanner> scanners) {
  std::uint64_t delay = 0;

  for (;;) {
    bool success = true;
    for (auto & scanner : scanners) {
      if (scanner.position++ == 0) { success = false; }
      if (scanner.position == scanner.length) scanner.position = 0;
    }
    if (success) break;
    delay++;
  }

  return delay;
}

} // namespace

TEST_SUITE("2017-12 examples") {
  TEST_CASE("example") {
    std::istringstream in {
      "0: 3\n"
      "1: 2\n"
      "4: 4\n"
      "6: 4\n"      
    };
    auto input = Parse(in);
    CHECK(Caught(input) == 24);
    CHECK(Delay(input) == 10);
  }
}

auto Main(std::istream & in, std::ostream & out) -> void
{
  auto input {Parse(in)};
  out << "Part 1: " << Caught(input) << std::endl;
  out << "Part 2: " << Delay(std::move(input)) << std::endl;
}