Detect Cycle in Linked List

MediumPython

Problem

How would you detect a cycle in a linked list?

Implement detect_cycle(nodes, head_index), where nodes[i] stores the index of the next node and -1 represents null. Return True if traversal from head_index revisits a node, otherwise return False.

Constraints

0 <= len(nodes) <= 500
Each next-node value is either -1 or an integer from 0 through len(nodes) - 1
head_index is -1 for an empty list or a valid node index
The input represents a singly linked structure

Function Signature

def detect_cycle(nodes, head_index):

CodePython 3

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