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     * [UC Berkeley Algorithms](https://archive.org/details/ucberkeley-webcast?&and[]=subject%3A%22Computer%20Science%22&and[]=subject%3A%22CS%22)
 
 ## Interview Books
-* [Competitive Programming 3 - Steven Halim & Felix Halim](https://www.amazon.com/Competitive-Programming-3rd-Steven-Halim/dp/B00FG8MNN8) 
+* Competitive Programming 4 - Steven Halim & Felix Halim
+   - [Book 1](https://www.lulu.com/shop/suhendry-effendy-and-felix-halim-and-steven-halim/competitive-programming-4-book-1/paperback/product-1q2pjn4n.html?page=1&pageSize=4)
+   - [Book 2](https://www.amazon.com/Competitive-Programming-4-Book-2/dp/B093K67NVN)
 * [Cracking The Coding Interview - Gayle Laakmann McDowell](https://www.amazon.com/Cracking-Coding-Interview-Programming-Questions/dp/0984782850/ref=sr_1_1?s=books&ie=UTF8)
 * [Cracking The PM Interview - Gayle Laakmann McDowell & Jackie Bavaro](https://www.amazon.com/Cracking-PM-Interview-Product-Technology-ebook/dp/B00ISYMUR6/ref=sr_1_1?s=books&ie=UTF8)
 * [Introduction to Algorithms -  Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest & Clifford Stein](https://www.amazon.com/Introduction-Algorithms-3rd-MIT-Press/dp/0262033844/ref=sr_1_1?ie=UTF8&qid=1490295989&sr=8-1&keywords=Introduction+to+Algorithms)