const float BETA = 3950; // should match the Beta Coefficient of the thermistor
int analogValue;
float celsius;

void setup() {
  // setup pinmodes
  pinMode(A0, INPUT);
  for(int i=3; i<=6; i++){
    pinMode(i, OUTPUT);
  }
}

void loop() {
  // read analog value
  analogValue = analogRead(A0);
  // calculate celsius degree
  celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;


  if(celsius < 0){
    // too cold
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  else if(celsius < 20){
    // cold
    digitalWrite(3, LOW);
    digitalWrite(4, HIGH);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  else if(celsius < 40){
    // warm
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
  }
  else {
    // hot
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, HIGH);
  }

  delay(80);


}