Competitive Programming / Data Structures / Algorithms

• Hacker Rank Hacker Rank
• Top Coder Top Coder
• Code Forces Code Forces
• Hacker Earth Hacker Earth
• Code Chef DSA Code Chef DSA
• Spoj Spoj
• OpenDSA course by Instructure Open DSA course
• Steven Skiena Youtube Steven Skiena - Youtube
• Library of algorithms https://www.jjj.de/fxt/#fxtbook

Curated set of problems

• Codility ** - Codility
• Code Zen by Coding Ninjas Code Zen
• Code Monk by Hacker Earth Code Monk
• Problems in TopCoder TopCoder - problems
• Geeks For Geeks - Data Structures* GFG DS
• Geeks For Geeks - Algorithms* GFG Algos
• Coding Game - Easy CodingGame
• Code Chef Code Chef - DSA
• HTML, CSS, JS, DS/Algo by Coding Ninjas InterQues

Articles for competitive programming

• Robert Eisele - XARG projects also on github and puzzles / solutions
• How to begin competitive programming HackerEarth guide
• How to begin competitive programming Coding Blocks guide
• Descriptions of many algorithms and data structures for competitive programming Cpp Algorithms Stanford - CS97si
• Important algorithms for competitive programming Algos - CodeChef
• Maths concepts Maths
• Competitive programming - warmup Warmup