Odd-even-number and Leap-year Programs

[jc-kirthi]

Hi, @pawanrajsingh2088

Basic:

1. odd_even_number.cpp
2. leap_year.cpp

These programs can be added.

Please do assign me this with hacktoberfest labels.

Thank you!

KIRTHI JC,
Hacktoberfest 25 Contributor

[suvendukungfu]

please assign this issue