You may have one variable "total" instead two: "left" and "right"

If char will be is '_' ??

would be better if you specify the size of the string

	StringBuilder stringBuilder = new StringBuilder(binary.size());

Can you review my solutions?

funny

not case sensitive

I have forgotten regExp^)

intresting

Coool

if you have 1_000_000 n your cicle work long.

Enterprise Edition!

NO READABLE

cool!

we can pass without invert[]

you create 2 objects :)