Are we really testing programming anymore?
Runtime performance is an advanced topic.

I special cased the loop increment to 2 after
a threshold and doubled the number of random number
evaluations from 30 to 60 but still times out.

Looking at primes from 1..100 shows 25 primes with
prime gap deltas of 2,4,6,8. I am not sure how to be
systematic in this effort. Is there a paper someone
can direct me to?

Richard
This is approximately logarithmic?

My solutions either run into memset (bool) space or runtime exceeded.
The straightforward wiki dfn causes runtime exceeded (attached below).

My for loop upper bound increment is i++.
Maybe it can be dynamically trimmed to avoid
visiting multiples of existing primes?

**Is that the right direction towards a solution? **

Random_Test

1 num:876527174 .. is not prime! 21 num:1577810551 .. is not prime!
2 num:1644030750 .. is not prime! 22 num:1266333403 .. is not prime!
3 num:1393969603 .. is not prime! 23 num:2132127515 .. is not prime!
4 num:1335491684 .. is not prime! 24 num:1281074547 .. is not prime!
5 num:1929713169 .. is not prime! 25 num:90046948 .. is not prime!
6 num:24193965 .. is not prime! 26 num:2068897426 .. is not prime!
7 num:49651675 .. is not prime! 27 num:1737718634 .. is not prime!
8 num:218588094 .. is not prime! 28 num:714922702 .. is not prime!
9 num:356028242 .. is not prime! 29 num:162692740 .. is not prime!
10 num:877418047 .. is not prime! 30 num:587217759 .. is not prime!
11 num:901310737 .. is not prime! 31 num:869667984 .. is not prime!
12 num:1107801141 .. is not prime! 32 num:1039219915 .. is not prime!
13 num:2099772465 .. is not prime! 33 num:83764861.. IS prime!
14 num:993022361 .. is not prime! 34 num:116153939 .. is not prime!
15 num:503688437 .. is not prime! 35 num:227227951 .. is not prime!
16 num:735156648 .. is not prime!
17 num:1089112823.. IS prime!
18 num:914354483 .. is not prime!
19 num:390465283 .. is not prime! STDERR
20 num:1819589577 .. is not prime! Execution Timed Out (12000 ms)