Coding Challenges

1st Challenge

Create a function that receives an integers array and returns the number that appeared only once.

Input	Output
(2,4,6,4,9,6,2)	9
(1,1,2)	2
(2,2,1)	1

2nd Challenge

Create a function that receives a string then it converts uppercase letters into lowercase and vice versa. The function then should print the converted value.

Input	Output
Hello	hELLO
Hi	hI
Hello World	hELLO wORLD
My name is Ali	mY NAME IS aLI
sHroog	ShROOG

3rd Challenge

Create a function that receives an array of items & arrays and returns one flattened array with all items exluding null values.

N	Input	Output
1	[1,[2,3,null,4],[null],5]	[1,2,3,4,5]
2	[7, 0,[null],[null, null, 9]]	[7, 0, 9]
3	[[null, 3], [2, 4, 5, null], 0, 8, 3]	[3, 2, 4, 5, 0, 8, 3]
4	[3, 5, [5, 9, 0]]	[3, 5, 5, 9, 0]

4th Challenge

Create a function that receives a string that contains combination of parentheses, square brackets, and curly braces. Then, it returns true if every opening bracket has a closing pair.

Input	Output
}{	false
()	true
)({}	false
({ }})	false
({ })	true
{{()}}	true
{{()}	false
[{}]	true
{[(}])	true
{[}])	false