Question 2
The picture shows a network of traffic lights. All lights switch simultaneously from red (grey circles) to green (white circles), and vice versa. Juan is stopped at the red entrance light and wants to leave through the exit. What is the least number of times he must stop at a red light after passing the entrance light? Assume changes are so slow that he could traverse an all-green network without stopping.
Editorial interpretation: Count stops after the entrance light has been passed; the initial wait at the entrance is excluded. Including it would give three waits.
Editorial interpretation: Count stops after the entrance light has been passed; the initial wait at the entrance is excluded. Including it would give three waits.