find_pairs.py

def binary_search_all(li, target, left, right):
    result = []

    while left <= right:
        mid = left + (right - left) // 2

        if li[mid][0] == target:
            result.append(li[mid][1])

            i = mid - 1
            while i >= left and li[i][0] == target:
                result.append(li[i][1])
                i -= 1

            i = mid + 1
            while i <= right and li[i][0] == target:
                result.append(li[i][1])
                i += 1

            return result
        elif li[mid][0] < target:
            left = mid + 1
        else:
            right = mid - 1

    return result


def find_pairs(li, k):
    arr_enumerated = [(num, index) for index, num in enumerate(li)]
    arr_enumerated.sort()

    pairs = []
    for num, index in arr_enumerated:
        diff = k - num
        diff_index_all = binary_search_all(arr_enumerated, diff, 0, len(li) - 1)

        for diff_index in diff_index_all:
            if index > diff_index:
                pairs.append((num, diff, index, diff_index))

    return pairs


def print_pairs(pairs):
    print("{")
    for num1, num2, index1, index2 in pairs:
        print(f"Numbers: {num1}, {num2} => Indexes: {index1}, {index2}")
    print("}")


print_pairs(find_pairs([1, 1, 2, 2], 3))
print_pairs(find_pairs([3, 5, 2, -4, 8, 11], 7))