How can you safely traverse and print a circular linked list without risking an infinite loop?

• A. Traverse until you reach a null pointer
• B. Start at head and stop when you return to head after visiting at least once
• C. Use a visited flag per node
• D. Recursively traverse until stack overflow

Answer: (B)

In a circular linked list there is no null terminator to signal the end, so you must detect when you’ve completed one full cycle. The reliable way is to start at the head, print it, and then move forward until you return to the head after visiting at least once. This ensures you traverse every node exactly one time and stop, since the traversal naturally cycles back to the starting node.

Handle the empty-list case first: if the head is null, print nothing. This method avoids infinite looping because the stop condition is returning to the starting node, which only happens after exactly one full loop.

Relying on a null pointer would fail here because there isn’t one in a circular list. Using a per-node visited flag is possible but introduces extra state to manage and isn’t as clean. Recursively traversing would also risk infinite recursion and stack overflow due to the cycle.