Docs: Added Solution to Leetcode 420

[shreyash3087]

Related Issue

Closes #1004

Description

This PR adds the solution to leetcode problem 420 (Strong Password Checker).

Type of PR

• Bug fix
• Feature enhancement
• Documentation update
• Other (specify): _______________

Screenshots / Videos (if applicable)

Checklist

• I have performed a self-review of my code.
• I have read and followed the Contribution Guidelines.
• I have tested the changes thoroughly before submitting this pull request.
• I have provided relevant issue numbers, screenshots, and videos after making the changes.
• I have commented my code, particularly in hard-to-understand areas.

Additional Context

N/A

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[deepsource-io]

Here's the code health analysis summary for commits 0145bf6..f5b1e09. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
JavaScript	✅ Success		View Check ↗

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[github-actions]

Great job, @shreyash3087! 🎉 Thank you for submitting your pull request to CodeHarborHub. We appreciate your contribution and enthusiasm! Our team will review it soon. If you have any questions or need further assistance, feel free to reach out. Thanks for contributing!

[shreyash3087]

@ajay-dhangar kindly put the labels and merge it if there is no issue

Thankyou

[ajay-dhangar]

Done

[ajay-dhangar]

@shreyash3087, you need to add something to this file to count its score on your leaderboard. Then, you can try it at the bottom.

---

<h2>Authors:</h2>

<div style={{display: 'flex', flexWrap: 'wrap', justifyContent: 'space-between', gap: '10px'}}>
{['github_username'].map(username => (
 <Author key={username} username={username} />
))}
</div>

for your author profile in docs