Minimize Change Output for Bitcoin transactions, naive implementation

pb.py

"""
Suppose you are given a list of possible Bitcoin that you control (inputs). You
need to pay someone exactly 0.71 BTC. How would you select exactly 2 inputs in
such a way as to minimize the change output if you could ignore fees? Write a
python function that selects the two inputs.
"""
from itertools import permutations

TEST_INPUTS = [0.21, 0.59, 1.34, 3.45, 0.3, 0.84, 0.53, 0.62, 0.70, 0.21, 0.44,
               0.28, 0.39, 200.9, 4.34]
PAYMENT = 0.71


def run(inputs, payment):
    """
    Runs the program and prints result to std out.
    """
    filtered_inputs = filter_larger_than_payment(inputs, payment)
    best_combo = find_best_combo(filtered_inputs, payment)
    print(best_combo)


def filter_larger_than_payment(inputs, payment):
    """
    Filters inputs that are larger than the payment since they can not be
    relevant for the solution.
    """
    return [input for input in inputs if input < payment]


def find_best_combo(inputs, payment):
    """
    Finds the smallest combination of inputs that are combined still larger
    than the payment.
    """
    best_combo = (payment, payment)

    for combo in permutations(inputs, 2):
        (val1, val2) = combo

        if val1 + val2 == payment:
            best_combo = combo
            break
        elif val1 + val2 < payment:
            continue
        elif val1 + val2 < best_combo[0] + best_combo[1]:
            best_combo = combo

    return best_combo


run(TEST_INPUTS, PAYMENT)