feat: add preOrder algorithm for tree data structure. test: add testc…

[Aryadev19]

…ases for preOrder algortihm

 know more

Describe your change:

• [x] Add an algorithm?
• [ ] Fix a bug or typo in an existing algorithm?
• [ ] Documentation change?

Checklist:

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized.
• [x] I know that pull requests will not be merged if they fail the automated tests.
• [x] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [x] All new JavaScript files are placed inside an existing directory.
• [x] All filenames should use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames. Example:UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not
• [ ] All new algorithms have a URL in their comments that points to Wikipedia or another similar explanation.
• [ ] If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[Aryadev19]

You are probably right, implementing all the methods in a tree class will be better. I am totally new to contributing to open source, so I am still learning about good test cases, I have one doubt one method is missing from the tree that is tree mirroring, I was thinking about doing that, so should it be a separate algorithm like in the python one or should I just update the tree file.

[appgurueu]

You should group algorithms working on the same tree structure in the same tree class. I assume you're going to implement a BinaryTree class?

[Aryadev19]

Yeah I think there's only a BST class, not binary tree, so I can implement binary tree and implement some of the methods, I'll work on that then!

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.