target = 2020
input_file = "/tmp/aocinput"

def find_sum_of_two():
    large_n = []
    small_n = []

    with open(input_file) as file:
        line = file.readline()
        while line and line != "\n":
            halftarget_count = 0

            number = int(line)
            if number > target/2:
                large_n.append(number)
            elif number == target/2:
                halftarget_count += 1
            else:
                small_n.append(number)

            if halftarget_count == 2:
                print(f"Found a sum : {target/2}*2 = {target}\nAnswer is {(target/2)**2}")
                break

            line = file.readline()

    for big_one in large_n:
        complement = target-big_one
        if complement in small_n:
            print(f"Found a sum : {big_one}+{complement} = {target}\nAnswer is {big_one*complement}")
            return

    print("No sum found that can reach {target}")

def sum_search(target_sum, inputs):
    lower = []
    upper = []

    for num in inputs:
        if num < target_sum/2:
            lower.append(num)
        else:
            upper.append(num)

    search_list = lower if len(lower) < len(upper) else upper
    iter_list = upper if len(lower) < len(upper) else lower

    for num in iter_list:
        if target_sum - num in search_list:
            return num, target_sum-num

    return False


def find_sum_of_three():
    data = []
    subtracted_to_target = []
    with open(input_file) as file:
        line = file.readline()
        while line and line != "\n":
            data.append(int(line))
            subtracted_to_target.append((target-data[-1],data[-1]))

            line = file.readline()

    data.sort()

    for sub_target in subtracted_to_target:
        result = sum_search(sub_target[0],data)
        if result:
            print(f"Sum found : {result[0]}+{result[1]}+{sub_target[1]} = {target}\nResult is {result[0]*result[1]*sub_target[1]}")
            return

    print("No sum found")