Evaluating student grades
Question
You are given a string representing all letter grades a student as earned. The record only contains the following three characters:
- 'A' : Excellent
- 'B' : Good
- 'C' : Average
- 'D' : Below Average
- 'F' : Deficient
A student will be given a diploma if their record has:
- Less than 5 D's
- Less than 2 F's
- No more than 3 consecutive D's
Given a string, write a function to return whether a given student will be given a diploma.