const byte N = 10; // number of cards
int numberArray[N];

long randomDealt;

void setup()
{
  Serial.begin(115200);
  Serial.print("reset  ");
  Serial.println(N);

  pinMode(2, INPUT_PULLUP);
}

void loop()
{
  for (int ii = 0; ii < 13; ii++) numberArray[ii] = -1;  // sentinel

//  deal4s();

  deal2Fi();
  
  if (0) for (int element : numberArray)
    Serial.print(element),Serial.print(" ");
  
  Serial.println("");
  Serial.println("");

  delay(777);
  while (digitalRead(2) == HIGH);
}

// Uniform Backward Inside-Out Fisher–Yates (safe)
void deal4s()
{
  for (int tt = N - 1; tt >= 0; --tt) {
    const int card = random(tt, N);     // Arduino: [tt, N)

    if (card != tt) {

      numberArray[tt] = numberArray[card];  // displace existing value
    }
    else {
      Serial.print("tt = card "); Serial.println(tt);;
    }
    numberArray[card] = tt;                 // insert new value

    printArray(tt, card);
  }
}




// Uniform Backward inside-out Fisher–Yates
void deal4()
{
  for (int tt = N - 1; tt >= 0; --tt) {
    const int card = random(tt, N);

    numberArray[tt]   = numberArray[card];
    numberArray[card] = tt;

//    if (1) printArray(tt, card);
  }
}

// Fisher Yates initialise and shuffle. oh, Knuth.
// this is "inside-out"
void deal2F()
{
  for (unsigned char tt = 0; tt < N; tt++) {
    unsigned char card = random(0, tt + 1);

    numberArray[tt] = numberArray[card];
    numberArray[card] = tt;

//    printArrayF(tt, card);
  }
}

char buffer[80];

void deal2Fi()
{
  for (unsigned char tt = 0; tt < N; tt++) {
    unsigned char card = random(0, tt + 1);   // upper was tt + 1

snprintf(buffer, 79, "%2d: array[%2d] (%2d) -> array[%2d] and %2d -> array[%2d]\n",
  tt, card, numberArray[card], tt, tt, card);

Serial.print(buffer);

    numberArray[tt] = numberArray[card];
    numberArray[card] = tt;
  }

  Serial.println("");
  printArrayP();
}

void printArrayP()
{
  for (int i = 0; i < N; i++) {
      Serial.print(numberArray[i]); Serial.print(" ");
  }

  Serial.println();
}

// for the backward order, shows the result building right to left
// to do. make this go from left OR right
// just use snprintf to format the lines, this breaks at N >= 11
void printArray(int slot, int card)
{
  Serial.print(slot); Serial.print(" : ");
  Serial.print(card); Serial.print(". ");

  for (int i = 0; i < N; i++) {
    if (i < slot) Serial.print("_ ");
    else {
      // numbers:
      //Serial.print(numberArray[i]);
      //Serial.print(' ');
      // or letters for <=26:
      Serial.print((char)('A' + numberArray[i])); Serial.print(' ');
    }
  }
  Serial.println();
}

// for the forward order?
void printArrayF(int slot, int card)
{
  Serial.print(slot); Serial.print(" : ");
  Serial.print(card); Serial.print(". ");

  for (unsigned char tt = 0; tt < N; tt++) {
    Serial.print(numberArray[tt]); Serial.print("  ");
  }
  Serial.println("");
}