leetcode-the-hard-way solution: 0015-3Sum-medium added

Change Summary

Provide summary of changes with issue number if any.

Checklist

If you haven't fulfilled the below requirements, your PR won't be reviewed.

General

[x] Make sure you've read CONTRIBUTING.md
[x] Make sure you've followed the template format
[x] Make sure you've started the app locally and verified all the content and all links (if applicable) must be accessible correctly
[x] Make sure you've applied LaTex for variables, formulas and time / space complexity instead of using backticks
[x] Make sure you've formatted your code well (Code Block is rendered using <Tabs/>) Below is a C++ example. You can include multiple langs using <TabItem/> if necessary

<Tabs>

<TabItem value="cpp" label="C++">
<SolutionAuthor name="@YOUR_ALIAS"/>

```cpp
// Your code goes here
// Prefer K&R Coding style
```

</TabItem>

</Tabs>

[x] Make sure you've explained your code well (write comments above each line - not inline)
[x] Make sure you've written your explanation well and it is easy to understand for beginners
[x] Make sure you've included Time & Space Complexity Analysis
[x] Make sure you've included a meaningful approach name for your solution. Don't leave it blank. e.g. ## Approach 1: Two Pointers.

For Tutorial Articles

[ ] Make sure you've explained your topic using 1 - 3 LC problems rather than using external problems. Solutions must be taken with explanations as well.
[ ] Make sure you've provided suggested problems at the end using the given format. See here as an example. If the target solution is not available, leave solutionLink blank.
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Oct 08 '22 05:10 saloni33

@vigneshshiv kindly review

Oct 08 '22 05:10 saloni33

Updated.

Oct 08 '22 06:10 saloni33

Is it ready for review?

Oct 09 '22 16:10 wingkwong

Is it ready for review?

Yes I have done required changes

Oct 10 '22 12:10 saloni33

Please click re-request review next time. Otherwise I'd assume it's still in progress.

Oct 10 '22 13:10 wingkwong

Please click re-request review next time. Otherwise I'd assume it's still in progress.

okay

Oct 10 '22 13:10 saloni33

@wingkwong kindly check

Oct 12 '22 12:10 saloni33

any update?

Nov 01 '22 16:11 wingkwong

Closing due to inactivity.

Nov 18 '22 11:11 wingkwong