HackerRank

Powerful coding training system. LintCode has the most interview problems covering Google, Facebook, Linkedin, Amazon, Microsoft and so on. We provide Chinese and English versions for coders around the world.

GeeksforGeeks | A computer science portal for geeks

Topcoder is home to the world’s largest community of designers, developers, and data scientists. Allowing you the freedom to start and execute faster.

Welcome To PKU JudgeOnline

Codewars is where developers achieve code mastery through challenge. Train on kata in the dojo and reach your highest potential.

VisuAlgo was conceptualised in 2011 by Dr Steven Halim as a tool to help his students better understand data structures and algorithms, by allowing them to learn the basics on their own and at their own pace. Together with his students from the National University of Singapore, a series of visualisations were developed and consolidated, from simple sorting algorithms to complex graph data structures. Though specifically designed for the use of NUS students taking various data structure and algorithm classes (CS1010, CS1020, CS2010, CS2020, and CS3233), as advocators of online learning, we hope that curious minds around the world will find these visualisations useful as well.