"""稳定证券键、边界优先保留与输入重排；全排列验收。"""
import itertools
import json

scores = {'A': 5, 'B': 4, 'C': 4, 'D': 4, 'E': 1}
held = {'A', 'C'}


def select(items, retain):
    return [s for s, value in sorted(items,
            key=lambda item: (-item[1], item[0] not in held if retain else False, item[0]))[:2]]


for perm in itertools.permutations(scores.items()):
    assert select(perm, True) == ['A', 'C']
    assert select(perm, False) == ['A', 'B']
naive1 = sorted(scores.items(), key=lambda x: -x[1])[:2]
naive2 = sorted(reversed(list(scores.items())), key=lambda x: -x[1])[:2]
assert [r[0] for r in naive1] != [r[0] for r in naive2]
assert select([('A', 5), ('B', 4), ('C', 3), ('D', 4), ('E', 1)], True) == ['A', 'B']
assert select([(s, v) for s, v in scores.items() if s != 'C'], True) == ['A', 'B']
retained_cash, id_cash = 200, 200 + 400 - 1 - 400 - 1
assert retained_cash + 800 == 1000 and id_cash + 800 == 998
print(json.dumps({'retain': select(scores.items(), True), 'identifier_only': select(scores.items(), False),
                  'permutations_checked': 120, 'retain_equity': 1000, 'identifier_equity': 998,
                  'identifier_orders': [['C', 'sell', 40, 10, 1], ['B', 'buy', 40, 10, 1]],
                  'naive_original': naive1, 'naive_reversed': naive2}))