lex.cpp

#include <algorithm>
#include <stdexcept>
#include <vector>

/**
 * @brief Find the best vector of costs arranged in descending order from a vector of vectors of costs.
 *
 * @tparam T A comparable type.
 * @param costs A vector of vectors of prioritized costs.
 * @param minimize Whether or not smaller values are better.
 * @return The best vector.
 */
template <typename T>
const std::vector<T> multi_lex(const std::vector<std::vector<T>>& costs, const bool& minimize) {
  if (costs.empty()) {
    throw std::length_error("There are no costs to compare!");
  }
  const unsigned int size = costs.at(0).size();
  for (const auto& i : costs) {
    if (i.size() != size) {
      throw std::length_error("Cost sizes don't match!");
    }
  }
  const auto comp = [minimize](T a, T b) { return minimize ? a < b : b < a; };
  std::vector<T> best{costs.at(0)};
  for (const auto& i : costs) {
    if (std::lexicographical_compare(best.begin(), best.end(), i.begin(), i.end(), comp)) best = i;
  }
  return best;
}