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Strings (Medium - Hard)

Manipulating strings and using string functions

Introduction

Welcome to your Python competitive programming journey! In this first tutorial, you'll explore the fundamentals of Python programming through various resources, set up a code editor, learn how to use these tutorials effectively, and learn how to practice competitive programming problems to continuously improve.​​

Tutorials

First, let's discuss how to utilize the tutorials. It is recommended to follow the sections and subsections in chronological order. However, feel free to skip a tutorial and come back to it at a later time.

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Each section will begin by teaching the content with text, visuals, and examples. Afterward, you can test your understanding with the mini-challenges, apply your concepts using the practice problems, and vote on the poll. The practice problems (mostly easiest to hardest, and ranging from easy to catastrophic) come from a variety of sources and have helpful hints if you need help. If you're stuck, viewing the solution is valuable - learn from the experience, and reflect on what you could've done differently. Be sure to implement it after getting ideas from the editorial! After solving a problem, reviewing other solutions can help you discover more efficient or elegant solutions. Understanding other methods will ultimately improve your intuition and implementation skills. Additional resources are also given in each section if applicable.​​

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If you are a teacher/club leader using these tutorials, feel free to use any materials here as a learning resource!

Guide to Competitive Programming

Competitive programming is all about applying algorithms and implementing them into code. First, you need to come up with a solution using problem solving, critical thinking, mathematics, and logic. To succeed, you must analyze problems effectively and view them from different perspectives. An algorithm for solving a problem needs to be accurate and also efficient (within the time and memory constraints of the problem). Understanding the theory behind algorithms and how to apply it effectively to problems is a crucial skill needed to succeed, as well as making observations and insights about the properties of the problem. Then, you need to implement your idea to code.

 

In competitive programming, your solution is graded by testing your code implementation against a set of test cases, checking the answer returned by your program for each test case. Your program must return the correct output and satisfy the time and memory limit. You'll need to adopt a good coding style that makes your code concise and clear, and you need to be good at implementation skills because you are running against the clock, so most of your time should be spent on coming up with the algorithm. A competitive math background can be beneficial for problems that involve mathematical insights. The most popular languages used in programming contests are C++, Java, and Python.​​

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Mastering competitive programming requires dedication, and you'll grow by spending time practicing problems and consistently participating in various programming contests like CodeEvolve, USACO, Codeforces, Leetcode, Codechef, and others.

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Here are the reasons why you should start competitive programming:

  • Enhances your thinking and intuition ability

  • Gives you a sense of accomplishment after solving a problem

  • Relevant in future technical interviews for software-related jobs and companies

  • Connects you to a community of people who share your passion for programming

Getting a Code Editor and Learning to Code

Now let's delve into installing and running your code on a code editor! Here are some code editors that can be used to run Python code locally:

You can also use an online editor:

I personally use the VS Code editor.​

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Now it's time to learn the basics of Python and its essential data structures. Python is a great option for competitive programming because of its simple, readable, and straightforward syntax, which makes implementing code and debugging easier. I recommend the following resources for learning the building blocks:

Make sure that you're comfortable with the following topics:

  • Variables and data types

  • Input/output (IO)

  • Loops/iteration

  • Conditionals (if/elif/else)

  • Logical and mathematical operators

  • Functions and basic recursion

  • Arrays (1D, 2D, and 3D lists, built-in sorting)

  • Sets, Dictionaries, and Tuples

  • Strings

While learning, try to build your own programs and tinker around to actively engage and apply the topics. An important note is that whenever you want to know how to do something or know the built-in method for something, always Google it so that you can learn from it.

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After becoming comfortable with Python, it's time to start solving problems. You'll increase your problem-solving and algorithmic programming skills by applying your knowledge. Work on 800-900 rated CodeChef or Codeforces problems, easy level Leetcode, and easy-medium level CodeEvolve. Start with easy problems, and then slowly increase the difficulty. Don't hesitate to check out other solutions to expand your skillset, even if you solved it!

Conclusion

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🧩 Mini-Challenge 🧩

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💡 Mini-Challenge Solution 💡

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⚔️ Problems ⚔️

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📊 Poll 📊

Vote on this interactive poll to share your opinion on different aspects of competitive programming such as favorite algorithm, data structure, or most challenging problem with real-time results!

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