day23.txt

#################### ANNOTATED ASSEMBLY ####################

        set b 65        # b = 65
        set c b         # c = 65
        jnz a 2         # if a {
        jnz 1 5         #
A:      mul b 100       #     mul_count += 1
        sub b -100000   #     b = 106500
        set c b         #
        sub c -17000    #     c = 123500
                        # }
                        # while true {
B:      set f 1         #     f = 1
        set d 2         #     d = 2
                        #     do {
E:      set e 2         #         e = 2
D:      set g d         #         do {
        mul g e         #             mul_count += 1
        sub g b         #
        jnz g 2         #             if d * e == b {
        set f 0         #                 f = 0
                        #             }
C:      sub e -1        #             e++
        set g e         #        
        sub g b         #        
        jnz g -8        #         } while e != b
        sub d -1        #         d++
        set g d         #    
        sub g b         #    
        jnz g -13       #     } while d != b
        jnz f 2         #     if f == 0 {
        sub h -1        #         h++
                        #     }
F:      set g b         #    
        sub g c         #    
        jnz g 2         #     if b == c {
        jnz 1 3         #         return
                        #     }
G:      sub b -17       #     b += 17
        jnz 1 -23       # }


#################### ANNOTATED C(ISH) ####################

b = 65                      # if A:
c = 65                      #     b = 106500
if a {                      #     c = b + 17000
    mul_count += 1          #     mul_count += 1
    b = 106500              # else:
    c = 123500              #     b = c = 65
}                           #
while true {                # for b in xrange(b, c + 1, 17):
    f = 1                   #     f = 1
    d = 2                   #     mul_count += (b - 2) ** 2
    do {                    #     for d in xrange(2, b):
        e = 2               #
        do {                #         for e in xrange(2, b):
            mul_count += 1  #
            if d * e == b { #             if d * e == b:
                f = 0       #                 f = 0
            }               #
            e++             #
        } while e != b      #
        d++                 #
    } while d != b          #
    if f == 0 {             #     if f == 0:
        h++                 #         h += 1
    }                       #
    if b == c {             #
        return              #
    }                       #
    b += 17                 #
}                           #


#################### ANNOTATED PYTHON(ISH) ####################

if A:
    b = 106500
    c = b + 17000
    mul_count += 1
else:
    b = c = 65

for b in xrange(b, c + 1, 17):  # h = len(filter(is_not_prime,
    f = 1                       #                xrange(b, c + 1, 17)))
    mul_count += (b - 2) ** 2   #
    for d in xrange(2, b):      #
        for e in xrange(2, b):  # mul_count = sum([
            if d * e == b:      #     (i - 2) ** 2 for i in xrange(...)])
                f = 0           #
    if f == 0:                  #
        h += 1                  #


#################### ANSWERS ####################

Part 1: we just have one iteration, and are looking for mul_count, which is
(65 - 2) ** 2 = 63 ** 2 = 3969

Part 2: we are looking for the number of primes in the given range,
106500 to 123500 inclusive, going in steps of 17.  106500 is 17 * 6264 + 12, so
we are looking for any i from 6264 to 7264 inclusive such that 17i + 12 is
prime.  The following mathematica command gives the answer:
In[1]:=  Length[Select[17 * Range[6264, 7264] + 12, Not@*PrimeQ]]
Out[1]:= 917