returning certain sum values of dictionary

Question

Basically this is a combination program. It sums up all values in dict1 and returns all key combinations that add to 100. I want to get the same result, but I don't want certain key/values to be in the same combination group. ie I don't want key 'a' to be in any combination group with key 'b', key 'c' not be in any combination group with 'd', etc.

import itertools
dict1 = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5, 'f':6, 'g':7, 'f':8}

def matches(d, target):
    # First try single items, then couples, then triplets etc.
    for num in range(1,len(d)+1):
        # Iterate over all possible combinations of length num
        for com in itertools.combinations(d.items(), num):
            # Does the sum of all second items per key/value pair match the target?
            if sum(item[1] for item in com) == target:
                # Yield one item at a time, so the caller can decide when to stop

                yield dict(com).keys()

for match in matches(dict1, 100):
    print(match)

Answer 1

The main problem is, that the logic of the program doesn't work in this form.

The maximum of sum(item[1] for item in com) is 30 , then the loops end. Thus function matches doesn't yield anything.