Formula to find median in Binary Search changed

[Souravjyoti]

Describe your change:

Finding median using the previous formula may carry the median value out of range. Therefore, updated the formula with a better one.

References

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
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• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
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[realDuYuanChao]

Thanks for your contribution.

[nirvanarsc]

Actually this change is not necessary. Above expression is already using a logical shift (three >>>) which will preserve the sign bit if a potential overflow happens when summing (left + right). For languages like C++ and others that only support arithmetic shift (two >>) above workaround is necessary.

TL;DR original code works fine