I should just return false whenever its invalid, then return true if it's passed. Then the solution is more elegant.

Yes for sure!

The compiler should be smart enough to get rid of them, but the boolean logic operations should be simplified.
Using bool for a variable name might not be the best practice. Using the bool variable at all seems pointless.

This is quite unreadable tbh.

Thanks

I did not really keep track of time, but I guess it took me 2-3 hours.

May I ask how long it took you ?

How long did it take you ?