Added new CP websites (#4025)

* Added new CP websites

* Added new CP websites

problem-sets-competitive-programming.md

@@ -10,6 +10,8 @@
 
 * [4Clojure](http://www.4clojure.com)
 * [A2 Online Judge](https://a2oj.com)
+* [AtCoder](https://atcoder.jp)
+* [Binary Search](https://binarysearch.com)
 * [Caribbean Online Judge](http://coj.uci.cu)
 * [Codeabbey](http://www.codeabbey.com)
 * [Codechef](https://www.codechef.com/contests)