#TASK

Given:
N sorted iterators of integers.

The task:
Implement iterator (Iterator<Integer>) that produces globally sorted sequence from the given N iterators.
Task must be solved in the most efficient way possible
(i.e it's not allowed  to copy entire content of iterators into some structure and then sort it).

For example:
Iterator A1: 6, 8, 19, 21, 32, 66, 67, 77, 89
Iterator A2: 1, 3, 5,  24, 33, 45, 57, 59, 89
Iterator A3: 2, 4, 9,  18, 22, 44, 46, 89, 89

Final globally sorted Iterator must produce:

1 (from A2)
2 (from A3)
3 (from A2)
4 (from A3)
5 (from A2)
6 (from A1)
8 (from A1)
9 (from A3)
18 (from A3)
19 (from A1)
21 (from A1)
22 (from A3)
...

#RESULT

see `AggregateIteratorTest` first function to follow the implementation.

run ./gradlew test to see result