combination type problem

I have a puzzling problem and I can't seem to find a reasonable solution.
For example I have a sequence of letters:
A B C D
A corresponds to the numbers 5 and 10;
B = 11
C = 6
D = 12 and 7;
I need to generate the different combinations in the same order as the original sequence of letters.
The results should be as follows.
5 11 6 12
10 11 6 12
5 11 6 7
10 11 6 7

I hope this makes sense and any help is greatly appreciated.

What have you done so far?

that seems to lend itself to a recursive solution.
have a function that takes a string (char *) as input

Code:

---

if the input is 0 (end of string), return
ch = first character in the string
for each number that ch as associated with it (could be one or more)
        print the number
        recursively call the function with the remaining characters

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then the issue is how to determine the numbers that are associated with each letter. for starters I would just use 'ifs' or 'switch' on the characters to get something working. then you could concoct a data structure that tells you the numbers for a given letter.