What is Algorithm? -  https://www.khanacademy.org/computing/computer-science/algorithms

Big-O Algorithm Complexity Cheat Sheet - http://www.bigocheatsheet.com/

Hackerrank Algorithms Section - https://www.hackerrank.com/domains/algorithms

GeekForGeeks Algorithms Section - https://www.geeksforgeeks.org/fundamentals-of-algorithms/

Princeton Java https://introcs.cs.princeton.edu/java/10elements/

HackerEarth Data Structures - https://www.hackerearth.com/practice/data-structures/arrays/1-d/tutorial/

HackerEarth Algorithms - https://www.hackerearth.com/practice/algorithms/searching/linear-search/tutorial/

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What is logarithm? - https://stackoverflow.com/questions/2307283/what-does-olog-n-mean-exactly

* What does the time complexity O(log n) actually mean? - https://hackernoon.com/what-does-the-time-complexity-o-log-n-actually-mean-45f94bb5bfbf