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Small nitpick: you don't need 16GiB, 2^31 bytes is "just" 2GiB. Doesn't contradict your point though.

Each element of the input array is at least 4 bytes, bringing it to 8GiB.

Not necessary. But, still, my work laptop from 2020 has 32Gb of memory. So, not that implausible.

Swap in an ArrayList and mock size() and you need a few bytes...