Leetcode/0273_Integer_to_English_Words.cpp at main · Nothing-avil/Leetcode · GitHub

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// ███████╗  █████╗  ███╗   ██╗ ██████╗   █████╗  ██████╗  ██████╗  ██╗  ██╗
// ██╔════╝ ██╔══██╗ ████╗  ██║ ██╔══██╗ ██╔══██╗ ██╔══██╗ ██╔══██╗ ██║  ██║
// ███████╗ ███████║ ██╔██╗ ██║ ██║  ██║ ███████║ ██████╔╝ ██████╔╝ ███████║
// ╚════██║ ██╔══██║ ██║╚██╗██║ ██║  ██║ ██╔══██║ ██╔═██╗  ██╔══██╗ ██╔══██║
// ███████║ ██║  ██║ ██║ ╚████║ ██████╔╝ ██║  ██║ ██║  ██╗ ██████╔╝ ██║  ██║
// ╚══════╝ ╚═╝  ╚═╝ ╚═╝  ╚═══╝ ╚═════╝  ╚═╝  ╚═╝ ╚═╝  ╚═╝ ╚═════╝  ╚═╝  ╚═╝
#pragma GCC optimize("Ofast", "inline", "ffast-math", "unroll-loops","no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native", "f16c")
auto init = []() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    return 'c';
}();
class Solution {
 public:
  string numberToWords(int num) {
    if (num == 0)
      return "Zero";
    return helper(num);
  }

 private:
  const vector<string> belowTwenty{
      "",        "One",     "Two",       "Three",    "Four",
      "Five",    "Six",     "Seven",     "Eight",    "Nine",
      "Ten",     "Eleven",  "Twelve",    "Thirteen", "Fourteen",
      "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};
  const vector<string> tens{"",      "",      "Twenty",  "Thirty", "Forty",
                            "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};

  string helper(int num) {
    string s;

    if (num < 20)
      s = belowTwenty.at(num);
    else if (num < 100)
      s = tens.at(num / 10) + " " + belowTwenty.at(num % 10);
    else if (num < 1000)
      s = helper(num / 100) + " Hundred " + helper(num % 100);
    else if (num < 1000000)
      s = helper(num / 1000) + " Thousand " + helper(num % 1000);
    else if (num < 1000000000)
      s = helper(num / 1000000) + " Million " + helper(num % 1000000);
    else
      s = helper(num / 1000000000) + " Billion " + helper(num % 1000000000);

    trim(s);
    return s;
  }

  void trim(string& s) {
    s.erase(0, s.find_first_not_of(' '));
    s.erase(s.find_last_not_of(' ') + 1);
  }
};