School Cafeteria's Trash Can Upgrade Project Lv.2

int trigPin = 9;
int echoPin = 8;
int led = 7;
int led2 = 6;
int led3 = 5;
int led4 = 4;
long distance;
long duration;
void setup() {
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode (led,OUTPUT);
pinMode (led2,OUTPUT);
pinMode (led3,OUTPUT);
pinMode (led4,OUTPUT);
}
void loop() {
  ultra();// put your main code here, to run repeatedly:
  Serial.println(distance);
  LV0();
  delay(50);
  LV1();
  delay(50);
  LV2();
  delay(50);
  LV3();
  delay(50);
  LV4();
  delay(50);
    if (distance>=5){
    digitalWrite(led4,LOW);
  }
}
void ultra(){ // Clears the trigPin
digitalWrite(trigPin, LOW);
delayMicroseconds(2);// Sets the trigPin on HIGH state for 10 micro seconds
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);// Reads the echoPin, returns the sound wave travel time in microseconds
duration = pulseIn(echoPin, HIGH);// Calculating the distance
distance= duration*0.034/2;
}
void LV0(){
  if(distance>30){
    digitalWrite(led,LOW);
    delay(100);
    digitalWrite(led2,LOW);
    delay(100);
    digitalWrite(led3,LOW);
    delay(100);
    digitalWrite(led4,LOW);
    delay(100);
  }
}
void LV1(){
  if(distance<=30 and distance>21){
    digitalWrite(led,HIGH);
    delay(100);
    digitalWrite(led,LOW);
    delay(100);
  }
}/*1단계 led만 점멸등 2,3,4단계는 항상 off*/
void LV2(){
  if(distance<=21 and distance>12){
    digitalWrite(led,HIGH);
    digitalWrite(led2,HIGH);
    delay(100);
    digitalWrite(led2,LOW);
    delay(100);
  }
}/*2단계 led만 점멸등 1단계는 항상 on 3,4단계는 항상 off*/
void LV3(){
  if (distance<=12 and distance>5){
    digitalWrite(led,HIGH);
    digitalWrite(led2,HIGH);
    digitalWrite(led3,HIGH);
    delay(100);
    digitalWrite(led3,LOW);
    delay(100);
  }
}/*3단계 led만 점멸등 1,2단계는 항상 on 4단계는 항상 off*/
void LV4(){
  if (distance<=5){
    digitalWrite(led,HIGH);
    digitalWrite(led2,HIGH);
    digitalWrite(led3,HIGH);
    digitalWrite(led4,HIGH);
  }
}/*4단계 led만 점멸등 1,2,3단계는 항상 on*/