#include <UltrasonicSensor.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

byte trigpin = 2;
byte echopin = 3;
byte yellowLED = 4;
byte redLED = 5;
float distance = 0;
UltrasonicSensor ultrasonic(trigpin, echopin);

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);

  lcd.init();
  lcd.backlight();

  pinMode(yellowLED, OUTPUT);
  pinMode(redLED, OUTPUT);
}

void loop() {

  distance = ultrasonic.distanceInCentimeters();

  Serial.print("Distance: ");
  Serial.println(distance);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Distance:");
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");

  if (distance > 100 && distance <= 200) {
    digitalWrite(yellowLED, HIGH);
    digitalWrite(redLED, LOW);
  } else if (distance <= 100) {
    digitalWrite(yellowLED, LOW);
    digitalWrite(redLED, HIGH);
  } else {
    digitalWrite(yellowLED, LOW);
    digitalWrite(redLED, LOW);
  }

  delay(200);
}