What is the optimal time complexity of solving Linked List Cycle?

The optimized solution achieves a time complexity of O(n) by using sorting, mathematical shortcuts, or hash table lookups.

What is the auxiliary space complexity for Linked List Cycle?

The space complexity is O(1) since we only use a minimal/constant amount of extra memory for tracking variables (or auxiliary space if dynamic structures are allocated).

What are the typical edge cases we must handle in Linked List Cycle?

Key edge cases include empty collections, negative or large bounds causing integer overflow, arrays with only one element, or inputs where target criteria are not met.

How can we optimize the brute force approach for Linked List Cycle?

Brute force methods often inspect all possible combinations. We optimize this by sorting the input list to enable binary search, or tracking processed items in a set to avoid redundant nested loop lookups.

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Linked List Cycle

Learn how to solve the 'Linked List Cycle' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

Given head, the head of a linked list, determine if the linked list has a cycle in it.

There is a cycle in a linked list if there is some node in the list that can be reached again by continuously following the next pointer. Internally, pos is used to denote the index of the node that tail's next pointer is connected to. Note that pos is not passed as a parameter.

Return true if there is a cycle in the linked list. Otherwise, return false.

The input is given as a list of values and an integer pos (the index where the tail connects to, -1 if no cycle). Implement a function hasCycle(head: list, pos: int) -> bool.

Constraints

•The number of nodes in the list is in the range [0, 10000]
•-100000 <= Node.val <= 100000
•pos is -1 or a valid index in the linked list

Examples

Example 1

Input

[3,2,0,-4], 1

Output

True

Explanation

There is a cycle: the tail node (-4) connects back to the node at index 1 (value 2).

Example 2

Input

[1,2], 0

Output

True

Explanation

There is a cycle: the tail node (2) connects back to the node at index 0 (value 1).

Example 3

Input

[1], -1

Output

False

Explanation

There is no cycle in the list.

Need a Hint?

Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.

Edge Cases to Watch

Empty list or null input variables
Single item lists/arrays
Extremely large input bounds causing integer or stack overflow

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