#### Overview of this book

Begin your journey into the fascinating world of algorithms with this comprehensive course. Starting with an introduction to the basics, you will learn about pseudocode and flowcharts, the fundamental tools for representing algorithms. As you progress, you'll delve into the efficiency of algorithms, understanding how to evaluate and optimize them for better performance. The course will also cover various basic algorithm types, providing a solid foundation for further exploration. You will explore specific categories of algorithms, including search and sort algorithms, which are crucial for managing and retrieving data efficiently. You will also learn about graph algorithms, which are essential for solving problems related to networks and relationships. Additionally, the course will introduce you to the data structures commonly used in algorithms. Towards the end, the focus shifts to algorithm design techniques and their real-world applications. You will discover various strategies for creating efficient and effective algorithms and see how these techniques are applied in real-world scenarios. By the end of the course, you will have a thorough understanding of algorithmic principles and be equipped with the skills to apply them in your technical career.
Free Chapter
Chapter 1: Introduction to Algorithms
Chapter 2: Pseudocode and Flowcharts
Chapter 3: Algorithm Efficiency
Chapter 4: Basic Algorithm Types
Chapter 5: Search Algorithms
Chapter 6: Sort Algorithms
Chapter 7: Graph Algorithms
Chapter 8: Data Structures Used in Algorithms
Chapter 9: Algorithm Design Techniques
Chapter 10: Real World Applications of Algorithms
Conclusion
Where to continue?

# 1.4 Practice Problems

Having covered the fundamentals of algorithms and computational thinking, it's now time to put these principles into practice. The problems in this section have been designed to help you think computationally and apply the concepts of decomposition, pattern recognition, abstraction, and algorithmic thinking. Don't worry if you can't solve a problem immediately - remember that part of computational thinking is iteration and refining your approach.

Problem Description: Write an algorithm to generate a password of length n. The password should be randomly generated and must include at least one uppercase letter, one lowercase letter, one digit, and one special character.

Hint: Consider decomposing the problem into parts - generating an uppercase letter, generating a lowercase letter, generating a digit, generating a special character, and then combining these parts.

Solution:

To solve this problem, we could create four functions to generate a random uppercase letter, a random lowercase letter, a random digit, and a random special character respectively. Then, we combine these randomly generated characters, and fill the rest of the password length with random characters from all groups.

Here's how we could write it in Python:

## Problem 2: Calendar Events

Problem Description: You have a list of events with their start times and end times (in 24-hour format). Write an algorithm to determine if any of the events overlap.

Hint: Look for patterns in how events overlap, and think about how you might abstract the problem to make it more manageable.

Solution:

First, we'll sort the list of events based on their start times. Then, we'll iterate through the sorted list and compare the end time of the current event to the start time of the next event. If the end time of the current event is later than the start time of the next event, then there is an overlap.

## Problem 3: Building a Pyramid

Problem Description: Given a number n, write an algorithm to print a pyramid of asterisks with n levels. For example, if n = 3, the output should be:

Hint: Decompose the problem into two parts - generating each level of the pyramid, and then combining the levels. Also, try to recognize patterns in the number of asterisks and spaces.

Solution:

This problem can be solved by printing each level of the pyramid one by one. At each level, we print some spaces, followed by some asterisks, and then some spaces again.

## Problem 4: Text Compression

Problem Description: Write an algorithm to compress a given string by replacing consecutive identical characters with the character followed by the number of times it appears. For example, the string "aaabbbbcc" should be compressed to "a3b4c2".

Hint: This problem can be approached using algorithmic thinking - devise a step-by-step process to traverse the string and keep track of the count of each character.

Solution:

We can solve this problem by iterating over the string and keeping track of the current character and its count. If the current character is different from the previous one, we add the previous character and its count to the compressed string and reset the count.

Remember, these problems are not just about finding the correct answer, but about understanding and applying computational thinking. Once you've attempted a problem, try to reflect on how you used decomposition, pattern recognition, abstraction, and algorithmic thinking. If you find a solution, consider how you might refine it to make it more efficient or more elegant.