Practice what you learn. Build real coding skills.
Strengthen your programming skills with coding problems, DSA challenges, algorithms, interview questions and real-world practice — from beginner to advanced.
function twoSum(nums, target) {
const map = new Map();
for (let i = 0; i < nums.length; i++) {
const complement = target - nums[i];
if (map.has(complement)) {
return [map.get(complement), i];
}
map.set(nums[i], i);
}
}Keep your coding streak alive.
Solve one carefully selected problem every day. Build consistency, improve your problem-solving skills, and create a habit of coding.
Practice at your level.
Start where you are and gradually move toward harder problems.
Choose what you want to master.
Focused practice tracks help you improve one skill at a time.
Data Structures
Practice arrays, strings, linked lists, stacks, queues, trees, graphs and more.
300+ ProblemsAlgorithms
Master searching, sorting, recursion, greedy, dynamic programming and graph algorithms.
250+ ProblemsJavaScript
Improve JavaScript fundamentals, modern syntax, logic and problem-solving.
150+ ProblemsPython
Practice Python programming, logic building, data structures and algorithms.
150+ ProblemsSQL
Work with queries, joins, aggregation, subqueries and real-world database problems.
100+ ProblemsWeb Development
Practice HTML, CSS, JavaScript and frontend development through practical challenges.
120+ ChallengesFind your next problem.
Search by problem name, topic, or difficulty.
Two Sum
Find two numbers in an array that add up to a given target.
Valid Parentheses
Determine whether brackets in a string are correctly balanced.
Binary Search
Implement binary search efficiently on a sorted collection.
Longest Substring
Find the longest substring without repeating characters.
Merge Intervals
Merge overlapping intervals into a minimal set of intervals.
LRU Cache
Design an efficient least-recently-used cache data structure.
Practice like you're preparing for the real thing.
Prepare for technical interviews with curated DSA, JavaScript, frontend, backend, SQL and system-design practice tracks.
A better way to build coding skills.
Don't just solve problems. Understand them, improve, and apply what you learn.
Learn
Understand the concept, pattern, algorithm or data structure before solving.
Practice
Solve progressively harder problems and strengthen your fundamentals.
Review
Study your mistakes, compare approaches and improve your solution.
Master
Build consistency, earn progress and move toward real-world projects.
Turn practice into measurable progress.
Later, connect this section to your CodeHarborHub account so learners can track solved problems, streaks, XP, achievements and topic mastery.
Learn together. Solve together. Grow together.
CodeHarborHub is built in the open. Contribute problems, improve solutions, share knowledge and help other learners.
Stop watching tutorials. Start solving.
Build stronger programming fundamentals through consistent practice, real problems and meaningful challenges.