enter code here
char cypherText[] = "LMU XOASR JCZIK VZN EODTUP ZHUC LMU GFWY PZBQ";
char plainText[sizeof(cypherText)];

char cypher[] = {'I', 'G', 'R', 'M', 'J', 'A', 'L', 'V', 'W', 'B', 'N', 'T', 'H', 'X', 'U', 'D', 'S', 'K', 'C', 'P', 'E', 'F', 'Z',
                 'Q', 'Y', 'O', ' ', 'n', '' };

// index returns an integer that can be used to find the plain text
// equivalent of a cypher text letter.
int index(char letter) {
   switch (letter)
   {
      case (' '): return 26;
      case ('n'): return 27;
      case (''): return 28;
      default: return (int) (letter - 'A');
   }
}

void setup() {
   // initialize serial communication at 9600 bits per second:
   Serial.begin(9600);

   // Fill the plainText array with null characters so that print
   // stops
   for (int i = 0; i < sizeof(plainText); i ++) {
      plainText[i] = '';
   }

   // Insert your code to decypher the message

   // Print the plainText
   Serial.print(plainText);
}

void loop() {

std::string encrypted_text;
for (size_t i = 0; i < sizeof(cypherText); ++i)
{
  const char c = cypherText[i];
  const cypher_index = index(c);
  encrypted_text += cypher[cypher_index];
}