Coding Challenges: Beginner Exercises and Practice Tips
Coding challenges are small programming exercises with a defined task, inputs, and expected results. They give you a way to practice loops, functions, and data handling without building an entire application. Start with a problem you can describe in plain English, then write the code and check it against examples.
You can use a language you already know. If you have not chosen one yet, the programming guide explains where each language fits. CodeWalkers has a history of PHP coding contests, but you do not need to enter a contest to try the exercises below.
What Are Coding Challenges Good For?
Coding challenges help you practice a specific skill, such as looping through a list or counting repeated values. Several solutions may produce the right result, with different costs in memory, speed, or readability.
A short challenge can warm you up the way a musician runs scales before a performance. However, exercises do not replace building an application. Projects also teach you to organize files, handle changing requirements, and maintain code that other people use.
Three Coding Challenges to Try
These exercises need variables, functions, conditions, and loops. The last two also use key-value collections. Use Python, PHP, JavaScript, or another language you are learning; no website, database, or extra package is required.
1. Add the Positive Numbers
Write a function that adds only the positive integers in a list, so [4, -2, 7, 0] returns 11. An empty list or a list containing only zero and negative numbers should return 0.
Start with a running total and inspect each number. Check a single positive number and an all-negative list before calling the function finished. This practices a loop and a condition; Python lists and loops are one way to get started.
2. Count Task Statuses
Count how often each status appears in a list, treating statuses as exact, case-sensitive strings. For ["open", "done", "open"], return counts of open = 2 and done = 1. An empty list should produce no status entries.
Use each status as a key and its count as the value. Check repeated statuses and a status that appears once. As an extra task, decide how to handle "Open" and "open" as the same status, then update your tests to match that rule.
3. Total Paid Orders by Customer
Given orders with a customer name, an amount in whole cents, and a paid flag, calculate each customer's paid total. Alice's paid orders of 1200 and 800 cents should total 2000. Exclude an unpaid order of 500 cents.
Assume valid records, nonnegative integer amounts, and customer names that match exactly. Include only customers with at least one paid order; no paid orders should produce an empty result. Check two customers and a zero-value paid order. Whole cents keep decimal rounding out of this exercise.
Once the function works, try the same task with rows in a database. The SQL guide explains the query basics you will need to filter records and group totals.
How Do You Solve a Coding Challenge?
Solve a coding challenge by stating the expected result, writing a simple solution, and checking ordinary and unusual inputs before optimizing it.
- Restate the rules. Write down the inputs, output, and limits. Decide what an empty input should do instead of guessing midway through the code.
- Work one example by hand. Trace the values you expect at each step. If you cannot explain the steps, reduce the problem first.
- Write the simplest working version. Use clear names and straightforward logic. Get the sample result right before trying to make the solution shorter or faster.
- Look for an input that breaks it. Try empty lists, repeated values, zero, and boundary values when the rules allow them. Save those cases so you can rerun them after a change.
- Compare approaches. After your attempt, read another solution and explain what it does differently. Optimize when the input limits or measured performance give you a reason.
A passing sample is a useful first check, not proof that every input works. For the order exercise, a solution that handles Alice correctly may still mix two customers' totals. Add a second customer to test that assumption.
Looking for an Old CodeWalkers Contest?
CodeWalkers previously ran PHP coding contests where readers' scripts competed against each other. This page is a starting point for practice, not a restored archive of those contest entries. The PHP guide covers current PHP techniques if an old contest link brought you here.
Does CodeWalkers Run Coding Contests Now?
CodeWalkers does not currently run a recurring coding contest schedule. The exercises on this page are self-paced practice, with no submission deadline, ranking, or prize.
There is no announced date for new contests. When you are ready to move from exercises to a project, the programming learning paths explain what to learn first and what to build.
Frequently Asked Questions
Are coding challenges the same as technical interview questions?
Coding challenges and technical interview questions overlap, but they serve different purposes. Practice exercises help you learn; interview tasks help an employer assess your skills. Either can use automated tests, and interview formats vary.
When should you look at a coding challenge solution?
Read a hint for a coding challenge when you can explain what you have tried and where you are stuck. There is no fixed time limit for practice. After reading a solution, close it and try to reproduce the approach without copying.
What is competitive programming?
Competitive programming is a timed contest in which participants solve programming problems under stated rules. Automated judges commonly check correctness and execution limits. Scoring varies by contest, so speed is not the only factor in every event.
Should you use AI to solve coding challenges?
Use AI for coding challenge hints or explanations when you are practicing, but write and check your own solution if you want to learn the skill. Ask for one hint rather than a complete answer. In an assessment or contest, follow the rules on outside assistance.