What are the best coding challenges to improve your skills?

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mohit vyas

If you want to improve your coding skills, here are some of the best coding challenges categorized by skill level and focus area:

Perfect for those learning syntax, logic, and problem-solving basics.

FizzBuzz – Print numbers 1-100, but replace multiples of 3 with "Fizz" and multiples of 5 with "Buzz."
Palindrome Checker – Check if a string reads the same forward and backward.
Reverse a String – Reverse a given string without using built-in functions.
Factorial Calculation – Compute the factorial of a number using recursion.
Find the Maximum Number in an Array – Without using built-in functions.

📌 Where to practice: [LeetCode (Easy), CodeWars (8kyu-7kyu), HackerRank (Warm-up Challenges)]

For those comfortable with basic programming and looking to improve efficiency.

Two Sum Problem – Given an array and a target sum, find two numbers that add up to it.
Merge Two Sorted Lists – Combine two sorted linked lists into one sorted list.
Balanced Parentheses – Check if a string of brackets is balanced {[()]}.
Binary Search Algorithm – Implement binary search on a sorted array.
Rotating an Array – Shift elements left or right by k positions.

📌 Where to practice: [LeetCode (Medium), CodeWars (6kyu-5kyu), HackerRank (Algorithms)]

For those mastering algorithms, data structures, and optimization.

Longest Substring Without Repeating Characters – Find the longest unique character substring.
Dijkstra’s Algorithm – Find the shortest path in a graph.
Knapsack Problem – Solve the 0/1 Knapsack problem using dynamic programming.
LRU Cache Implementation – Implement a Least Recently Used (LRU) cache.
Trie Data Structure – Implement a Trie for efficient prefix searching.

📌 Where to practice: [LeetCode (Hard), CodeWars (4kyu-2kyu), TopCoder, Codeforces]

For those looking to sharpen speed and problem-solving skills under constraints.

Graph Traversal (BFS & DFS) – Solve maze problems, connected components, etc.
Segment Tree Implementation – Solve range query problems efficiently.
Bit Manipulation Problems – XOR, AND, OR optimizations.
Game Theory Problems – Find optimal strategies in turn-based games.

📌 Where to practice: [Codeforces, AtCoder, USACO, Google Code Jam]

For software engineers preparing for interviews or designing scalable applications.

URL Shortener – Design a scalable TinyURL system.
Rate Limiter – Implement a system that limits requests per second.
Cache Mechanism – Design a caching strategy for high-traffic websites.
Distributed Task Scheduler – Build a scheduler that efficiently distributes tasks.

📌 Where to practice: [Grokking the System Design Interview, InterviewBit, LeetCode System Design]

For those diving into AI and ML-related problem-solving.

Titanic Survival Prediction – Predict who survives the Titanic disaster (Kaggle).
Handwritten Digit Recognition – Implement a neural network to classify digits (MNIST dataset).
Stock Price Prediction – Use machine learning models for time-series forecasting.