For me implementing the data structure and it's operations made the difference between shallow and deep knowledge. There are a lot of data structures and I did

For me implementing the data structure and it's operations made the difference between shallow and deep knowledge. There are a lot of data structures and I did not see anyone post a basic list so let me provide one, because once you know what you should seek things will be much easier. Data structures: - linked list (single,double) - array list - hash map with different implementations - binary tree(and tree traversing, depth/breadth first search) - red-black tree - self balancing tree - stack - heap - queue - set (with funny set operations like intersection) - B and B* tree Read about their strengths and weaknesses. With every data structure comes operations. More or less the same with a few speciality but their implementations are vastly different. You should try to implement the same operations at every data structure: - Find an element - Find min/max - Add / delete an element - Sort the data Take time to implement the standard sorting algorithms for a list to understand the speed implications: quicksort, bubblesort, heapsort, radix sort, bucket sort If you look for other algorithmic challenges I suggest checking out graph algorithms. Dijkstra and A* are the most famous.