#include <LiquidCrystal_I2C.h>

int array[11] = {30,31,32,33,34,35,36,37,38,39, 40} ;
int array[15] = {1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000. 8500, 9000, 9500, 10000} ;

int buttonPin = 4;
int buzzer = 25
long ran;
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup()
{
  pinMode(buttonPin, INPUT_PULLUP); // define o pino do BotaoPin como entrada "INPUT"
  pinMode(buzzer, OUTPUT);

  Serial.begin(115200);

  // next 3 lines are for randomizing the randomgenerator.
  Serial.println("press a key");
  while (Serial.available() ==0);
  randomSeed(micros() +  Serial.read());
  
  // this is the trick
  for (int i= 0; i< 11; i++) 
  {
    int pos = random(12);
    int t = array[i];   
    array[i] = array[pos];
    array[pos] = t;
  }

  for (int i= 0; i< 11; i++)
  {
    Serial.print(i);
    Serial.print(": ");
    Serial.println(array[i]);
  }
}



void loop()
{
  while (digitalRead(buttonPin) == HIGH);
  digitalWrite(buzzer, HIGH);
  delay(random(200, 3001));
  digitalWrite(buzzer, LOW);
}