six seven

src/main-solution-6.cpp

@@ -85,14 +85,19 @@ std::string solution(const std::string &S) {
     return result;
 }
 
-std::string generate_testcase(std::size_t length, std::vector<char> charset, std::mt19937 generator, std::uniform_int_distribution<size_t> dist){
+std::string generate_testcase(std::size_t length, std::vector<char> charset, std::ifstream& urandom){
   if(length==0 || charset.size()==0) return "";
 
   std::string result = {};
   result.resize(length);
 
+  thread_local std::vector<unsigned char> buffer = std::vector<unsigned char>{};
+  buffer.resize(length);
+
+  urandom.read(reinterpret_cast<char*>(buffer.data()), length);
+
   for (size_t i= {0}; i<length; i++) {
-    result.at(i)=charset.at(dist(generator)); 
+    result.at(i)=charset.at(buffer.at(i) % charset.size()); 
   }
   return result;
 }
@@ -113,12 +118,11 @@ int main(){
     spdlog::error("FS error {}", e.what());
     return 1;
   }
-  std::random_device random_device = std::random_device{};
+  std::ifstream urandom = std::ifstream{"/dev/urandom", std::ios::in | std::ios::binary};
-  std::mt19937 generator = std::mt19937{random_device()};
+
-  std::uniform_int_distribution<std::size_t> dist (0, charset.size()-1);
   spdlog::info("Solution to testcase 0 is: {}", solution("67A6"));
-  for (size_t i = 0; i < 500; i++) {
+  for (size_t i = 50; i < 100; i++) {
-    std::string input = generate_testcase(i,charset, generator, dist);
+    std::string input = generate_testcase(i,charset, urandom);
     std::string output = solution(input);
 
     std::ofstream input_file = std::ofstream{fmt::format("{}/{}.in", folder.string(), i)};