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 focus on the following problem:

**Given a string, calculate its length.**

If you are preparing for an interview or trying to understand the notion of recursion to solve a problem, I hope this lesson is helpful to you. 

Python has a built-in `len()` function which returns the length of a string. This is the standard way to obtain the length of a string in Python. 

input_str = "LucidProgramming"
print(len(input_str))

# Iterative Approach
Now we are going to code the same functionality ourselves in Python. Let's begin with the iterative approach. 

# Iterative length calculation: O(n)
def iterative_str_len(input_str):
    input_str_len = 0
    for i in range(len(input_str)):
        input_str_len += 1
    return input_str_len

On **line 3**, `input_str_len` is initialized to `0`. Then using a `for` loop on **line 4**, `input_str` is iterated character by character and `input_str_len` is incremented by `1` in each iteration on **line 5**. Finally, the final value of `input_str_len` is returned from the function on **line 6**. As the entire length of the string is traversed once, the time complexity for this solution is thus $O(n)$ where $n$ is the length of the string. 

# Recursive Approach 

Let's go ahead and have a look at the recursive approach:

In this lesson, you will learn how to calculate the length of a string using both an iterative and recursive approach in Python.

Introduction

Stack

Singly Linked Lists

Circular Linked Lists

Doubly Linked Lists

Arrays

Binary Trees

Binary Search Trees

Binary Search

Recursion

String Processing

Calculate String Length

Iterative Approach