HappyCerberus

uint64_t top_three(const std::vector<std::string>& data) {
  auto by_elf = data |
	  // group by elf: range{range{string}}
      std::views::lazy_split(std::string{}) |
	  // sum up the calories for each elf: range{uint64_t}	
      std::views::transform([](const auto& elf) -> uint64_t {
          // std::string -> uint64_t
          auto to_unsigned = 
            [](const auto& in) { return std::stoull(in); };
          // make a view of uint64_t: range{string} -> range{uint64_t}

HappyCerberus

uint64_t max_calories(const std::vector<std::string>& data) {
  auto by_elf = data |
	  // group by elf: range{range{string}}
      std::views::lazy_split(std::string{}) | 
      // sum up the calories for each elf: range{uint64_t}	
      std::views::transform([](const auto& elf) -> uint64_t {
          // std::string -> uint64_t
          auto to_unsigned = 
            [](const auto& in) { return std::stoull(in); };
          // make a view of uint64_t: range{string} -> range{uint64_t}

HappyCerberus

build --color=yes
build --cxxopt=-std=c++20
build --cxxopt=-pedantic
build --cxxopt=-Wall
build --cxxopt=-Wextra
build --cxxopt=-Werror

build:debug --cxxopt=-ggdb3

HappyCerberus

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "com_google_googletest",
    strip_prefix = "googletest-609281088cfefc76f9d0ce82e1ff6c30cc3591e5",
    urls = ["https://github.com/google/googletest/archive/609281088cfefc76f9d0ce82e1ff6c30cc3591e5.zip"],
)

HappyCerberus

load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")

cc_library(
    name = "trivial",
    srcs = ["trivial.cc"],
    hdrs = ["trivial.h"],
)

cc_library(
    name = "sliding",

HappyCerberus

uint32_t count_increasing_windows(std::istream &input) {
  uint32_t e1 = 0, e2 = 0, e3 = 0, prev_sum = std::numeric_limits<uint32_t>::max(), drop = 2, cnt = 0;
  for (uint32_t v : std::ranges::istream_view<uint32_t>(input)) {
    e1 = std::exchange(e2, std::exchange(e3, v));
    if (drop > 0) {
      drop--;
      continue;
    }
    if (std::exchange(prev_sum, e1 + e2 + e3) < e1 + e2 + e3)
      cnt++;

HappyCerberus

int main(int argc, char *argv[]) {
  if (argc != 2) {
    std::cerr << "This program expects one parameter that is the input file to read.\n";
    return 1;
  }
  std::ifstream input(argv[1]);
  if (!input.is_open()) {
    std::cerr << "Failed to open file.\n";
    return 1;
  }

HappyCerberus

uint32_t count_increasing_windows(std::istream &input) {
  auto sliding_window_view = std::ranges::istream_view<uint32_t>(input) 
    | std::ranges::views::transform([e1 = 0, e2 = 0, e3 = 0](uint32_t curr) mutable {
        e1 = std::exchange(e2, std::exchange(e3, curr));
        return e1 + e2 + e3;
        });

  return std::ranges::count_if(sliding_window_view, 
                               [prev = std::numeric_limits<uint32_t>::max(), drop = 2]
                               (uint32_t curr) mutable {

HappyCerberus

TEST(SlidingTest, Simple) {
  std::vector<std::pair<std::string, uint32_t>> inputs = {
      {"", 0},                                        // not enough elements for a window
      {"0 1", 0},                                     // not enough elements for a window
      {"0 1 0", 0},                                   // a single window
      {"0 0 0 0 0 0", 0},                             // monotonic, no increase
      {"0 1 2 3", 1},                                 // two windows, increasing
      {"3 2 1 0", 0},                                 // two windows, decreasing
      {"0 1 0 1 0 1", 2},                             // 1, 2, 1, 2 - two increasing
      {"199 200 208 210 200 207 240 269 260 263", 5}, // from aoc

HappyCerberus

int main(int argc, char *argv[]) {
  if (argc != 2) {
    std::cerr << "This program expects one parameter that is the input file to read.\n";
    return 1;
  }
  std::ifstream input(argv[1]);
  if (!input.is_open()) {
    std::cerr << "Failed to open file.\n";
    return 1;
  }