Discover data structures and algorithms using Python. Gain insights into solving real-world problems and typical interview questions with detailed reviews, explanations, and hands-on coding exercises.

Data structures and algorithms are among the most fundamental concepts of Computer Science. Whether it’s real-world problems you’re trying to solve or the typical coding question asked in an interview, almost every problem requires you to demonstrate a deep understanding of data structures and algorithms. 

This course is a detailed review of some of the most common data structures and algorithms that you’ll see in interviews and your everyday work. With implementation details, thorough explanations, and hands-on coding exercises, you’ll quickly gain the confidence you need to solve any problem, no matter the situation.

Data Structures and Algorithms in Python

In this lesson, we investigate how to split one circular linked list into two separate circular linked lists and then code the solution in Python.

First of all, let's clarify what we mean by splitting a circular linked list by taking a look at the illustration below. 

To approach this problem, we'll find the length of the circular linked list and calculate the midpoint. Once that is done, we'll split the linked list around the midpoint. One half will be made by trimming the original linked list while the rest of the elements will be pushed into a new circular linked list. 

# `__len__()`

Let's see how we calculate the length of a circular linked list in Python:

def __len__(self):
  cur = self.head
  count = 0
  while cur:
    count += 1
    cur = cur.next
    if cur == self.head:
      break
  return count

# Explanation
The `__len__` method has been defined with underscores before and after the `len` keyword so that it overrides the `len` method to operate on a circular linked list. 

Calculating the length of the circular linked list is very straightforward. We declare `cur` equal to `self.head` on **line 2** to give a start for traversing the circular linked list. `count` is set to `0` initially on **line 3**. Next, we traverse the circular linked list using a `while` loop on **line 4** by updating `cur` to `cur.next` on **line 6**. On **line 5**, we increment `count` to keep track of the number of nodes in a circular linked list. If `cur` becomes equal to `self.head`, we break out of the loop (**lines 7-8**). Finally, we `return` count on **line 9**.

As you see, the length method was as simple as that. Now let's go over the `split_list` method.

# Implementation

In this lesson, you will learn how to split a circular linked list into two halves in Python.  

Introduction

Stack

Singly Linked Lists

Circular Linked Lists

Doubly Linked Lists

Arrays

Binary Trees

Binary Search Trees

Binary Search

Recursion

String Processing

Split Linked List into Two Halves

`len()`

Explanation