Algorithm
Binary Search, merge sort, quick sort, graph search - BFS, DFS, hashing, bloom filter, merkle tree
System Design
DNS, Load Balancer, Databases, CDN, Sequencer, Distributed monitorring/logging, Distributed cache/search, Distributed messaging queue / pub-sub, Distributed task scheduler
Machine Learning
Supervised - Regression, Decision Tree, Random forest, XGBoost, unsupervised - Clustering
Data Engineering and Analytics
Python Pandas, Dask, Spark, HDFS