Hacktoberfest2K21

Hello all, Let's contribute to open source.
Steps to contribute :

Name		Name	Last commit message	Last commit date
Latest commit History 57 Commits
Basic Calculator.cpp		Basic Calculator.cpp
BinaryTree		BinaryTree
Contributors.md		Contributors.md
Equinox.cpp		Equinox.cpp
IP-finder.py		IP-finder.py
Leader_Element.java		Leader_Element.java
Next_permutation.cpp		Next_permutation.cpp
README.md		README.md
Remove Invalid Parentheses.cpp		Remove Invalid Parentheses.cpp
The Skyline Problem.cpp		The Skyline Problem.cpp
a1.cpp		a1.cpp
bubble sort(sorting lexicographically dictionary).cpp		bubble sort(sorting lexicographically dictionary).cpp
calculator.py		calculator.py
count of unique digit numbers.cpp		count of unique digit numbers.cpp
hello.c		hello.c
hello.cpp		hello.cpp
hello.java		hello.java
hello.py		hello.py
mxevnsub_codechef.cpp		mxevnsub_codechef.cpp
name		name
p23.cpp		p23.cpp
p33.cpp		p33.cpp
problem152.cpp		problem152.cpp
r1.cpp		r1.cpp
r3.cpp		r3.cpp
u3.cpp		u3.cpp

Provide feedback