function getCombinations(digits) {
  // Mapping digits to letter
  const digitToChar = {
      '1': 'A', '2': 'B', '3': 'C', '4': 'D', '5': 'E', '6': 'F', '7': 'G', '8': 'H', '9': 'I', '10': 'J', '11': 'K', '12': 'L', '13': 'M', '14': 'N', '15': 'O', '16': 'P', '17': 'Q', '18': 'R', '19': 'S', '20': 'T', '21': 'U', '22': 'V', '23': 'W', '24': 'X', '25': 'Y', '26': 'Z'
    };

  // Store valid array
  const combinations = [];

  // Recursion
  function backtrack(start, path) {
    // // When reached the end of the digits, add the combination to the array
    if (start === digits.length) {
      combinations.push(path);
      return;
    }
    // Add letter from 1digit
    const singleDigit = digits[start];
    const singleDigitChar = digitToChar[singleDigit];
    if (singleDigitChar) {
      backtrack(start + 1, path + singleDigitChar);
    }

    // Add letters from two digits if still available
    if (start < digits.length - 1) {
      const twoDigits = digits.slice(start, start + 2);
      const twoDigitsChar = digitToChar[twoDigits];
      if (twoDigitsChar) {
        backtrack(start + 2, path + twoDigitsChar);
      }
    }
  }
  // Invoke recursive function initial value
  backtrack(0, '');
  return combinations;
}
const DIGITS = "1243752521494312";
const combinations = getCombinations(DIGITS);

console.log(`Jumlah Kombinasi ada ${combinations.length}`);
combinations.forEach((combination, index) => {
  console.log(`[${index}] => ${combination}`);
});