aocpp/2017/05.cpp

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

#include <doctest.h>

#include <aocpp/Startup.hpp>

namespace {

auto Parse(std::istream & in) -> std::vector<std::int64_t> {
  std::vector<std::int64_t> result;
  std::int64_t x;
  while (in >> x) {
    result.push_back(x);
  }
  return result;
}

auto Run1(std::vector<std::int64_t> program) -> std::size_t {
  std::int64_t cursor = 0;
  std::size_t n = 0;

  while (0 <= cursor && cursor < program.size()) {
    cursor += program[cursor]++;
    n++;
  }

  return n;
}

auto Run2(std::vector<std::int64_t> program) -> std::size_t {
  std::int64_t cursor = 0;
  std::size_t n = 0;

  while (0 <= cursor && cursor < program.size()) {
    auto & p = program[cursor];
    cursor += p;
    p += p >= 3 ? -1 : 1;
    n++;
  }

  return n;
}

} // namespace

TEST_SUITE("2017-05 examples") {
  TEST_CASE("example") {
    std::istringstream in { "0\n3\n0\n1\n-3\n" };
    auto input = Parse(in);
    CHECK(Run1(input) == 5);
    CHECK(Run2(input) == 10);
  }
}

auto Main(std::istream & in, std::ostream & out) -> void
{
  auto input {Parse(in)};
  out << "Part 1: " << Run1(input) << std::endl;
  out << "Part 2: " << Run2(std::move(input)) << std::endl;
}