Given a linked list, how can you determine if it contains a cycle?

Practice Questions

Q1
Given a linked list, how can you determine if it contains a cycle?
  1. Using a hash table
  2. Using two pointers
  3. Using recursion
  4. All of the above

Questions & Step-by-Step Solutions

Given a linked list, how can you determine if it contains a cycle?
  • Step 1: Understand what a linked list is. A linked list is a series of nodes where each node points to the next one.
  • Step 2: Know what a cycle in a linked list means. A cycle occurs when a node points back to a previous node instead of pointing to null.
  • Step 3: Choose a method to detect the cycle. You can use one of the following methods: a hash table, two pointers, or recursion.
  • Step 4: If using a hash table, create an empty table. As you traverse the linked list, add each visited node to the table. If you encounter a node that is already in the table, there is a cycle.
  • Step 5: If using two pointers, initialize two pointers (slow and fast). Move the slow pointer one step at a time and the fast pointer two steps at a time. If they meet, there is a cycle.
  • Step 6: If using recursion, keep track of visited nodes in a set. As you recursively visit each node, check if it has been visited before. If yes, there is a cycle.
  • Step 7: Return the result indicating whether a cycle was found or not.
  • Cycle Detection in Linked Lists – Understanding how to identify if a linked list has a cycle using various methods.
  • Data Structures – Knowledge of linked lists and hash tables as data structures.
  • Algorithmic Techniques – Familiarity with two-pointer technique and recursion in algorithm design.
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