// Determine if a string has all-unique characters.

#define CATCH_CONFIG_MAIN
#include <catch.hpp>

#include <string>

#include <fmt/format.h>

std::string urlify(std::string orig, int length) {
  // Start writing at the back of the string.
  auto write = orig.end();

  for (auto read = orig.begin() + length; read != orig.begin();) {
    read--;
    if (*read == ' ') {
      *--write = '0';
      *--write = '2';
      *--write = '%';
    } else {
      *--write = *read;
    }
  }
  return std::string(write, orig.end());
}

TEST_CASE("cc13", "urlify") {
  REQUIRE(urlify("Mr John Smith        ", 13) == "Mr%20John%20Smith");
}