capitalize

#include <string>
#include <cctype>

std::string capitalize(const std::string& word) {
  if (word.empty()) return word;
  std::string result = word;
  result[0] = std::toupper(result[0]);
  for (size_t i = 1; i < result.size(); ++i) {
    result[i] = std::tolower(result[i]);
  }
  return result;
}