Linked list is a basic lesson in C, but it's fun to implement them.
Define the structure
constructor
Why write this, because each manual malloc will be redundant, borrowed from the C++ new
Classic interview question, the difference between new and malloc
but cpp suggests using unique_ptr instead of bare pointers
About malloc without type conversion
Constructing a linked table
Print the linked table
nth
join_list
Insert node after
for example
delete nth node
it has boundary problem, use empty node to solve it.
