#include <DHT.h>
DHT dht(2,DHT22);
int redPin = 18;
int yellowPin = 19;
int greenPin = 21;
void setup()
{
  Serial.begin(9600);
  dht.begin();
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
}

void loop()
{
  float t = dht.readTemperature();
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.println(" *C ");

  if (t > 50) {
    digitalWrite(redPin, HIGH);
    digitalWrite(yellowPin, LOW);
    digitalWrite(greenPin, LOW);
  } else if (t < 20) {
    digitalWrite(redPin, LOW);
    digitalWrite(yellowPin, LOW);
    digitalWrite(greenPin, HIGH);
  } else {
    digitalWrite(redPin, LOW);
    digitalWrite(yellowPin, HIGH);
    digitalWrite(greenPin, LOW);
  }

  delay(500);
}