Quote:
Need regular expression to check the password policy
No, you 'want', but it is the wrong tool for the problem.
If password was "ABCDEF12$", RegEx would be Ok, but anything can be mixed, this is what makes the RegEx not appropriate.
You need to build a little piece of code like
set Counters
scan each char in password
categorize the current char
update marching Counter
check if Counters match the policy.