Group By Clause Based On Condition

tblScore contains score for each problem

id problemID score
------------------------
1 1 10
2 2 30

tblSubmission contains problem submissions for each user

id user problemID accepted
-----------------------------------------------
1 UserA 1 0
2 UserA 1 0
3 UserA 1 1
4 UserA 2 1
5 UserB 1 0
6 UserB 1 1
7 UserB 2 1

For UserA :
- For problemID 1
-> submitted three times
-> rejected for first two submission and accepted on third submission.
- For problemID 2
-> submitted one time
-> accepted on first submission

For UserB :
- For problemID 1
-> submitted two times
-> rejected for first submission and accepted on second submission.
- For problemID 2
-> submitted one time
-> accepted on first submission

Now I would like to process the table and want to get the following result :

user Score
--------------------------
UserA 36 (6 + 30)
UserB 38 (8 + 30)

Explanation :
- For each rejected submission, a -2 point penalty.
- UserA have submitted probelmID 1
- > score of problemID 1 is 10.
- > first two times rejectd
- > third time accepted.
-> score = 10 - 4 = 6
- UserA have submitted problemID 2
- > score of problemID 2 is 30
- > first time accepted. No penalty will be counted
- > score = 30

so final score for UserA = 30 + 6 = 36

Similar for UserB.