protected override string?SolvePartOne()
{
var p = new Day18.SoundProgram(Input);
var ret = true;
while (ret)
{
ret = p.Run();
}
return(p.mulCount.ToString());
}
protected override string?SolvePartTwo()
{
var p = new Day18.SoundProgram(Input);
/* Refactored into psuedo batch:
* b = 93
* c = b
* if (a != 0) goto A
* goto B
* A: mul b 100
* b += 100000
* c = b
* c += 17000
* B: f = 1
* d = 2
* E: e = 2
* D: g = d
* g *= e
* g -= b
* if (g != 0) goto C
* f = 0
* C: e += 1
* g = e
* g -= b
* if (g != 0) goto D
* d += 1
* g = d
* g -= b
* if (g != 0) goto E
* if (f != 0) goto F
* h += 1
* F: g = b
* g -= c
* if (g != 0) goto G
* goto H (EXIT)
* G: b += 17
* goto B
* H: (EXIT)
*/
/* Reduced into psuedo-C
* b = 93
* c = b
* if (a != 0) {
* b = 109300
* c = 126300
* }
*
* while(true) {
* f = 1
* d = 2
* do {
* e = 2
* do {
* if (d * e == b) f = 0
* e += 1
* } while(e != b)
* d += 1
* } while (d != b)
* // For every number d = 2 to b (109300):
* // For every number e = 2 to b (109300):
* // Check if e*d is a factor of b, if so, f is zero
*
* if (f == 0) h += 1
* // Count if we found a factor in any of the list
*
* if (b-c == 0) break
*
* b += 17
* // Since c is 17,000 larger than b, this loop runs 1001 times
* // NOT 1000 because the check is on the bottom
* }
*
* H:
* (EXIT)
*/
// Solution: Counting the number of NOT prime numbers between 109300 and 126317 (1001 * 17) numbers.
var h = Enumerable.Range(0, 1001).Count(index =>
{
// We want to know what is or isn't a divisor here
var num = 109300 + (17 * index);
return(num.GetDivisors().Count() > 2);
});
return(h.ToString());
}