Question 1

How do you detect a cycle in a linked list?

Accepted Answer

Floyd's Tortoise and Hare algorithm is a classic solution. Use two pointers, one moving one step at a time (tortoise) and the other moving two steps at a time (hare). If they meet, there's a cycle.

Question 2

How do you find the middle element of a linked list in one pass?

Accepted Answer

Use two pointers, a slow pointer and a fast pointer. The slow pointer moves one step at a time, while the fast pointer moves two steps. When the fast pointer reaches the end, the slow pointer will be at the middle.

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