[Issue] Resolve part of 167 & 165

[xxks-kkk]

Summary

Resolves: part of issue #167 and part of issue #165

For #167, this PR handles the test infrastructure of linked list (i.e., we can now properly test all the linked list problem locally with the JSON representation of linked list as the input)

For #165, this PR moves cppinclude out of leetcode directory and move it into the include directory.

Main Techniques:

Runtime Complexity Analysis

Space Complexity Analysis

Testing

The testing for functions in LinkedListRandom class is done by usage. In this case, we invoke them in LC138 (see PR #168) implementation and make sure they are working properly.

Performance

Performance Metrics from OJ Platform

Performance Improved Since Last Change

Implementation Notice

We use JSONCpp to parse the JSON input string. The version included in the repo has commit id: 2703c306a3168e15613d94e57fb8832138d9155d.

The implementation of list2list uses the idea of BFS when handling the objects within each level of JSON DOM and we uses the idea of LC138 (#168) to add the random pointers in the generated linked list.

The implementation of printList uses the idea of LC206. Reverse Linked List's recursive approach.

Implementation Tricks

To Do

We can replace Node *head = new Node(0, nullptr, nullptr); with std::shared_ptr<Node> head(new Node(0, nullptr, nullptr)); but whether std::shared_ptr is right one to use and the following error triggered at auto curr = head; requires further investigation. In general, how we can incorporate smart pointers in the linked list implementation requires further study.

To Learn

we use std::unqiue_ptr in const std::unique_ptr<Json::CharReader> reader(builder.newCharReader()); and we need to investigate further on unique_ptr topic with related smart pointers.

Questions

Language

• const int rawJsonLength = static_cast<int>(rawJson.length()); uses static_cast that casts size_t (the unsigned int) into int, which is signed. Here, we use static_cast to cast a larger arithmetic type to a smaller type. Without static_cast, compiler often generates a warning for assignments of a larger arithmetic type to a smaller type. Once we do an explicit cast, the warning message is turned off. We can also use static_cast to perform conversion that is not done by compiler automatically

void* p = &d; // ok: address of any nonconst object can be stored in a void* 
double *dp = static_cast<double*>(p); // // ok: converts void* back to the original pointer type

Failure Attempts