Codeforces Round #588 (Div. 2) D. Marcin and Training Camp
Codeforces Round #590 (Div. 3) B2. Social Network (hard version)
Codeforces Round #585 (Div. 2) B. The Number of Products
MongoDB基本概念
MongoDB基本命令
MongoDB常见问题
MongoDB副本集
Zookeeper Java 客户端
MongoDB安装