Find Loop Start

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Introduction

In computer science, a linked list is a linear collection of data elements, in which linear order is not given by their physical placement in memory. Instead, each element points to the next. A linked list is a dynamic data structure, which means that we can add or remove elements from it at any time. In this challenge, we will be looking at how to find the start of a linked list loop.


Skills Graph

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Find Loop Start

Problem

Given a singly linked list, we need to find the start of a loop if it exists. A loop is defined as a node in the list that points to a previous node, creating a cycle. If there is no loop, we return None. If there is a loop, we return the node where the loop starts.

Requirements

To solve this problem, we need to consider the following requirements:

  • The linked list is a singly linked list.
  • We cannot assume that we are always passed a circular linked list.
  • When we find a loop, we return the node where the loop starts.
  • We can assume that we already have a linked list class that can be used for this problem.

Example Usage

Here are some examples of how this function can be used:

  • Empty list -> None
  • Not a circular linked list -> None
    • One element
    • Two or more elements
  • Circular linked list general case

Summary

In this challenge, we learned how to find the start of a linked list loop. We looked at the requirements for solving this problem and saw some examples of how this function can be used. By understanding the concept of linked lists and loops, we can create more efficient and dynamic data structures in our programs.

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