Difference between HackerRank, LeetCode, topcoder and Codeforces
A comparison of the four competitive programming contest websites:
HackerRank: https://www.hackerrank.com/
LeetCode: https://leetcode.com/
topcoder: https://www.topcoder.com/
Codeforces: http://codeforces.com/
ICPC: https://icpc.baylor.edu/
IOI: http://www.ioinformatics.org/index.shtml
topcoder Point Erosion: https://community.topcoder.com/tc?d1=...
Codeforces Point Erosion: http://codeforces.com/blog/entry/456
Twitter: / code_report
Github: https://github.com/codereport