Part 1
In the first part, the goal is to count how many times the circular safe dial stops directly on position 0 after completing a rotation instruction. Starting at position 50 on a 100-number dial (0–99), each step specifies a direction—left towards lower numbers or right towards higher numbers—and a distance to rotate. By tracking the position modulo 100 after applying each rotation in sequence, the total number of times the dial lands on 0 is determined.
Part 2
For the second part, the challenge shifts to counting every single instance where a click causes the dial to pass over or land on position 0, including full revolutions during a single instruction. Rather than only checking the final position after a rotation, the total distance traveled is used to calculate how many times position 0 is hit or crossed along the path before the dial reaches its final destination for that instruction.