Data Structure and Algorithm is one of the essential topics for programmers, both to get a job and do well on Job. Good knowledge of data structure and algorithm is the foundation of writing good code. If you are familiar with essential data structures like an array, string, linked list, tree, map, and advanced data structure likeTries, AVL trees, etc and know when to use which data structure and compute the CPU and memory cost of your code in terms Even though you don't need to write your own array, linked list or hashtable, given every major programming SKD provides them like JDK or C++ STL library, you will need to understand them so that you can use them in right place. Using the right data structure can drastically improve the performance of an algorithm.