The problem being contributed must either be a simple **file** (**Eg.** [`kruskal-algorithm.cpp`](./algorithms/CPlusPlus/Graphs/kruskal-algorithm.cpp), [`linear-search.java`](./algorithms/Java/searching/linear-search.java)) or a more complex **directory** ([`palindrome/`](./algorithms/Rust/strings/palindrome)). This is a unit `problem`.
The directory tree has the following convention of `algorithms/{language}/{category}/{problem}`, where `{language}` represents the language code of the problem (**Eg.** `CPlusPlus` for C++, `CSharp` for C# etc.), `{category}` is the topic or category of the problem being contributed (**Eg.** `strings`, `sorting`, `linked-lists` etc.), and `{problem}` is a conforming name to the problem (**Eg.** `linear-search.cpp`, `palindrome`, `queue-linked-list.cpp` etc.)
1. Create a new folder and an index for it inside (a readme, `README.md` file).
2. To each new index file, write the readme with your `problem` in it ([Markdown Documentation](https://guides.github.com/features/mastering-markdown/)).
3. The folder name can also only contain **lowercase characters** and **dashes** or **hyphens** (`-`) (Eg. `strings``sorting` etc.)
The file should conform to the `problem` specification, and the extension (**Eg.** `linear-search.java`, `kruskal-algorithm.cpp`, `count-inversions.js` etc.)
Observation : The Nth node from the end is (K-N+1)th node from the beginning.
So the problem simplifies down to that we have to find (K-N+1)th node from the beginning.
One way of doing it is to find the length (K) of the linked list in one pass and then in the second pass move (K-N+1) step from the beginning to reach the Nth node from the end.
To do it in one pass. Let’s take the first pointer and move N step from the beginning. Now the first pointer is (K-N+1) steps away from the last node, which is the same number of steps the second pointer require to move from the beginning to reach the Nth node from the end.
The source code files, should either be in `src/` folder (**Eg.** `src/main.cpp` or `src/main.js`) or the root folder (**Eg.** `palindrome.go` or `App.java`) where `ext` is the file extension for the specific programming language.
Again, the source codes must conform to a valid file structure convention that the programming language enforces.
