first three days

day2/CMakeLists.txt

@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 3.10)
+
+# Project name and version
+project(Day2 VERSION 1.0)
+
+# Set default build type
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE Debug)
+endif()
+
+# 1. This is the critical line for Clangd. 
+# It generates the file clangd reads to know where headers are.
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Debug and Release flags
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -O0 -Wall -Wextra")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3")
+
+# Specify C standard
+set(CMAKE_CXX_STANDARD 23)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Add include directory
+include_directories(${PROJECT_SOURCE_DIR}/include)
+
+# Add executable
+add_executable(${PROJECT_NAME} 
+    src/main.cpp
+)

day2/Makefile

@@ -0,0 +1,13 @@
+
+
+clear:
+	rm -rf build/*
+
+run:
+	cp input.txt build
+	cp input_test.txt build
+	cd build && cmake .. && make && ./Day2 input_test.txt
+
+release:
+	cp input.txt build
+	cd build && cmake .. -DCMAKE_BUILD_TYPE=Release && make && ./Day2 input.txt

day2/flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1756787288,
+        "narHash": "sha256-rw/PHa1cqiePdBxhF66V7R+WAP8WekQ0mCDG4CFqT8Y=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d0fc30899600b9b3466ddb260fd83deb486c32f1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

day2/flake.nix

@@ -0,0 +1,58 @@
+{
+  description = "A Nix-flake-based C/C++ development environment";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs =
+    { self, nixpkgs }:
+    let
+      supportedSystems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+      forEachSupportedSystem =
+        f:
+        nixpkgs.lib.genAttrs supportedSystems (
+          system:
+          f {
+            pkgs = import nixpkgs { inherit system; };
+          }
+        );
+    in
+    {
+      devShells = forEachSupportedSystem (
+        { pkgs }:
+        {
+          default =
+            pkgs.mkShell.override
+              {
+                # Override stdenv in order to change compiler:
+                # stdenv = pkgs.clangStdenv;
+              }
+
+              {
+                nativeBuildInputs = with pkgs; [
+                  pkg-config
+                ];
+                packages =
+                  with pkgs;
+                  [
+                    clang-tools
+                    cmake
+                    codespell
+                    cppcheck
+                    doxygen
+                    gtest
+                    lcov
+                    nodejs
+                    vscode-extensions.vadimcn.vscode-lldb
+                  ]
+                  ++ (if system == "aarch64-darwin" then [ ] else [ gdb ]);
+                CODELLDB_PATH = "${pkgs.vscode-extensions.vadimcn.vscode-lldb}/share/vscode/extensions/vadimcn.vscode-lldb/adapter/codelldb";
+              };
+        }
+      );
+    };
+}

day2/input_test.txt

@@ -0,0 +1 @@
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124

day2/src/main.cpp

@@ -0,0 +1,111 @@
+#include <cmath>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+
+long check_num_part2(const std::string &num_str) {
+  if (num_str.length() == 2) {
+    if (num_str[0] == num_str[1]) {
+      return std::stol(num_str);
+    }
+    return 0;
+  }
+
+  size_t half = std::ceil(num_str.length() / 2);
+  for (size_t j = 0; j <= half; j++) {
+    auto sub = num_str.substr(0, j);
+    auto rest = num_str.substr(j);
+    if (sub.empty() || rest.empty()) {
+      continue;
+    }
+    int matched = 0;
+    bool all_matched = true;
+    for (size_t k = 0; k < rest.length(); k += sub.length()) {
+      auto rest_sub = rest.substr(k, sub.length());
+      if (sub != rest_sub) {
+        all_matched = false;
+        break;
+      } else {
+        matched += 1;
+      }
+    }
+    if (all_matched && matched >= 1) {
+      return std::stol(num_str);
+    }
+  }
+  return 0;
+}
+
+long check_range(const std::string &range, bool part_2) {
+  auto pos = range.find('-');
+  long count = 0;
+  std::cout << "Checking range " << range << std::endl;
+  if (pos != std::string::npos) {
+    auto range_start = range.substr(0, pos);
+    auto range_end = range.substr(pos + 1);
+    long rstart = std::stol(range_start);
+    long rend = std::stol(range_end);
+    for (long i = rstart; i < rend + 1; i++) {
+      auto istr = std::to_string(i);
+      if (!part_2) {
+        if (istr.length() % 2 == 0) {
+          auto first_half = istr.substr(0, istr.length() / 2);
+          auto second_half = istr.substr(istr.length() / 2);
+          count += (first_half == second_half) ? i : 0;
+        }
+      } else {
+        count += check_num_part2(istr);
+      }
+    }
+  } else {
+    std::cout << "Invalid range format: " << range << std::endl;
+    std::exit(1);
+  }
+
+  std::cout << "count: " << count << std::endl;
+  return count;
+}
+
+std::tuple<long, long> parse_input_file(const std::string &path,
+                                        bool do_part_2_only) {
+  std::ifstream file;
+  std::string line;
+
+  file.open(path);
+  long part_1 = 0;
+  long part_2 = 0;
+  if (file.is_open()) {
+    std::getline(file, line);
+    auto pos = line.find_first_of(',');
+    while (pos != std::string::npos) {
+      auto range = line.substr(0, pos);
+      if (!do_part_2_only)
+        part_1 += check_range(range, false);
+      part_2 += check_range(range, true);
+      line = line.substr(pos + 1);
+      pos = line.find_first_of(',');
+    }
+    if (line.find_first_of('-') != std::string::npos) {
+      if (!do_part_2_only)
+        part_1 += check_range(line, false);
+      part_2 += check_range(line, true);
+    }
+    file.close();
+  } else {
+    std::cout << "Failed to open file: " << path << std::endl;
+  }
+
+  return {part_1, part_2};
+}
+
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    std::cout << "One argument required: input txt" << std::endl;
+  }
+
+  auto results = parse_input_file(argv[1], true);
+  std::cout << "Part 1: " << std::get<0>(results) << std::endl;
+  std::cout << "Part 2: " << std::get<1>(results) << std::endl;
+
+  return 0;
+}