some trashy codes
*.h: functions declarations
*.cpp: functions implements
*.hpp: templates
linear-list-|
├──my_circular_list.hpp
├──my_singly_list.hpp
├──my_stack.hpp
└──my_vector.hpp
tree-|
└──tree_node.hpp
└──binary_tree.hpp
├──express_tree.hpp
└──binary_search_tree.h -> binary_search_tree.cpp
others-|
└──expression_calculate.h -> expression_calculate.cpp