Traffic light algortihm

 int RED=5; // define the value for the red LED pin

int YELLOW=11; // define the value for the yellow LED pin

int GREEN=3; // define the value for the green LED pin

void setup() {

  pinMode(GREEN, OUTPUT); // declare the green pin as output  

  pinMode(YELLOW, OUTPUT); // declare the yellow pin as output

  pinMode(RED, OUTPUT); // declare the red pin as output  

}

void loop() {

 

 digitalWrite(RED, HIGH); // turn on the green LED

 delay(2000); // wait for 2 seconds

 digitalWrite(RED, LOW); // turn off the green LED

 delay(500); // wait for half a second

 

 digitalWrite(YELLOW, HIGH); // turn on the yellow LED

 delay(2000); // wait for 2 seconds

 digitalWrite(YELLOW, LOW); // turn off the yellow LED

 delay(500); // wait for half a second

 digitalWrite(GREEN, HIGH); // turn on the red LED

 delay(3000); // wait for 2 seconds

 digitalWrite(GREEN, LOW); // turn off the red LED

 delay(500); // wait for half a second

 }