03. Trees-and-Traversals - 01 (solved by Niki), 02., 03. solved
04. Dictionary-HashTables-Sets -  03. solved, 04. partially (only Add() method implemented)
05. Advanced-Data-Structures - 01., 02. - solved; 03. - NOT
06. Data-Structures-Efficiency - 01., 02. - solved; 03. - NOT
07. Sorting-and-Searching-Algorithms - all implemented, but Quicksort() and MergeSort() method