Day16.cpp

day16.cpp

#include <chrono>
#include <iostream>
#include <string>

int main(int argc, char**) {
  auto start = std::chrono::high_resolution_clock::now();
  uint LIM{argc > 1 ? 35651584U : 272U};
  std::string in;
  in.reserve(LIM << 1); // big buffer
  std::cin >> in;
  while (in.size() < LIM) {
    in.push_back('0');
    auto b = in.rbegin();
    while (++b != in.rend())
      in.push_back(*b ^ 1);
  }
  in.resize(LIM);
  while (!(in.size() & 1)) {
    auto w = in.begin();
    for (auto r = in.cbegin(); r != in.cend(); r += 2)
      *w++ = '0' + (*r == *(r + 1));
    in.resize(in.size() >> 1);
  }
  auto stop = std::chrono::high_resolution_clock::now();
  std::cout << in << std::endl;
  std::cout << std::chrono::duration_cast<std::chrono::microseconds>(stop - start).count() << " microseconds" << std::endl;
}