Sums of List of Integers

Given an array of integers, give all possible ways the integers can be added to a certain value.

The output should be a list of lists containing all correct sums.
The resulting list should not contain duplicates.
The resulting sums should be in increasing order (i.e. sorted)

Example:

Give sums to 12:
   ✓ [1,2,3,3,5,7] => [5, 7], [2, 3, 7], [1, 3, 3, 5]
   X [1,2,3,3,5,7] => [7, 5], [2, 3, 7], [1, 3, 3, 5]
   X [1,2,3,3,5,7] => [7, 5], [2, 3, 7], [2, 3, 7], [1, 3, 3, 5]

Solution

import itertools

def equals_sum(num_arr, total):
    res = []
    for i in range(1, len(num_arr) + 1):
        for c in itertools.combinations(num_arr, i):
            if sum(c) == total:
                res.append(list(c))
                res[-1].sort()
    res = list(k for k,_ in itertools.groupby(res))
    return res