On Wednesday, 9 February 2022 at 10:03:21 UTC, MichaelBi wrote:
day6 of the advent of code 2021 needs to handle an array of
10^12 length, or even bigger... plus change elements and append
elements. normal implementation such as length, appender and
ref element etc, seems cannot handle that big array? is there
any alternative data structure or algorithm can handle such
large array properly? thanks.
Use a memorymapped file that holds the array values, in theory it
can be infinite then.
Since an array has a known size for each entry then you can treat
the file as an array.
Let's say you have an array of ints.
For a memorymapped file you obviously only have bytes to work
with, so each entry will be 4 bytes, since a 32 bit integer (int)
is 4 bytes.
So to read something at a specific index you simply do N x I
where N is the size of the type and I is the index you want to
read at.
Otherwise the size of an array cannot exceed the RAM you have, if
your system can't use diskspace as RAM of course.
