expense_report = []

with open('day1/input') as reader:
    expense_report.extend([int(l) for l in reader.readlines()])

expense_report.sort()

def calc_two(sub_set, absolute):
    first_i = 0
    second_i = len(sub_set) - 1
    first = sub_set[first_i]
    second = sub_set[second_i]

    while first_i < second_i and first + second + absolute != 2020:
        if first + second + absolute > 2020:
            second_i -= 1
            second = sub_set[second_i]
        else:
            first_i += 1
            first = sub_set[first_i]
    if first_i < second_i:
        return (first_i, second_i, first, second)
    return None

# part one
# first_i = 0
# second_i = len(expense_report) - 1
# first = expense_report[first_i]
# second = expense_report[second_i]
#
# while first + second != 2020:
#     if first + second > 2020:
#         second_i -= 1
#         second = expense_report[second_i]
#     else:
#         first_i += 1
#         first = expense_report[first_i]

first_i, second_i, first, second = calc_two(expense_report, 0)

print(first, second)
print(first * second)

# second part

for i in range(len(expense_report) - 1):
    res = calc_two(expense_report[i+1:], expense_report[i])
    if res is not None:
        print(res[2], res[3], expense_report[i])
        print(res[2] * res[3] * expense_report[i])
        break

# second part better?
# does not work! and probably never will!

# first_i = 0
# second_i = 1
# third_i = len(expense_report) - 1
# first = expense_report[first_i]
# second = expense_report[second_i]
# third = expense_report[third_i]
#
# up_with_second = first + second + third < 2020
#
# while first + second + third != 2020:
#     if first + second + third > 2020:
#         if up_with_second:
#             if second_i+1 == third_i:
#                 second_i -= 1
#                 second = expense_report[second_i]
#             third_i -= 1
#             third = expense_report[third_i]
#         else:
#             if second_i-1 != first_i:
#                 second_i -= 1
#                 second = expense_report[second_i]
#             else:
#                 third_i -= 1
#                 third = expense_report[third_i]
#                 up_with_second = True
#     else:
#         if up_with_second:
#             if second_i+1 != third_i:
#                 second_i += 1
#                 second = expense_report[second_i]
#             else:
#                 first_i += 1
#                 first = expense_report[first_i]
#                 up_with_second = False
#         else:
#             if second_i-1 == first_i:
#                 second_i += 1
#                 second = expense_report[second_i]
#             first_i += 1
#             first = expense_report[first_i]
#
#
# print(first, second, third)
# print(first * second * third)