aocpp/2017/01.cpp

#include <cstddef>
#include <cstdint>
#include <iostream>
#include <string>

#include <doctest.h>

#include <aocpp/Startup.hpp>

namespace {

auto Captcha(std::string const& input, std::size_t offset) -> std::int64_t {
  std::int64_t acc = 0;
  std::size_t const n = input.size();
  for (std::size_t i = 0; i < n; ++i) {
    if (input[i] == input[(i+offset)%n]) {
      acc += input[i] - '0';
    }
  }
  return acc;
}

auto Part1(std::string const& input) -> std::int64_t {
  return Captcha(input, 1);
}

auto Part2(std::string const& input) -> std::int64_t {
  return Captcha(input, input.size() / 2);
}

} // namespace

TEST_SUITE("2017-01 examples") {
  TEST_CASE("part 1") {
    CHECK(Part1("1122") == 3);
    CHECK(Part1("1111") == 4);
    CHECK(Part1("1234") == 0);
    CHECK(Part1("91212129") == 9);
  }
  TEST_CASE("part 2") {
    CHECK(Part2("1212") == 6);
    CHECK(Part2("1221") == 0);
    CHECK(Part2("123425") == 4);
    CHECK(Part2("123123") == 12);
    CHECK(Part2("12131415") == 4);
  }
}

auto Main(std::istream & in, std::ostream & out) -> void
{
  std::string input;
  std::getline(in, input);
  out << "Part 1: " << Part1(input) << std::endl;
  out << "Part 2: " << Part2(input) << std::endl;
}