AoC, day 23, puzzle 2

asm.py

# Step-by-step reverse engineering of day 23 / problem 2.

# Initial statate:
# `a` register set to 0, all others to 0.

# 1. set b 93
# 2. set c b
# 3. jnz a 2 (to:x0)
# 4. jnz 1 5 (to:x1)
# 5. mul b 100 (from:x0)
# 6. sub b -100000
# 7. set c b
# 8. sub c -17000
# 9. set f 1 (from:x1, from:x7)
# 10. set d 2
# 11. set e 2 (from:x4)
# 12. set g d (from:x3)
# 13. mul g e
# 14. sub g b
# 15. jnz g 2 (to:x2)
# 16. set f 0
# 17. sub e -1 (from:x2)
# 18. set g e
# 19. sub g b
# 20. jnz g -8 (to:x3)
# 21. sub d -1
# 22. set g d
# 23. sub g b
# 24. jnz g -13 (to:x4)
# 25. jnz f 2 (to:x5)
# 26. sub h -1
# 27. set g b (from:x5)
# 28. sub g c
# 29. jnz g 2 (to:x6)
# 30. jnz 1 3 (to:EXIT)
# 31. sub b -17 (from:x6)
# 32. jnz 1 -23 (to:x7)

def puzzle2():
    a = 1
    b, c, d, e, f, g, h = 0
    return h

# Pre-jump instructions, x2, and x5 jumps removed.
# `a` register removed as well, since it does not appear anyhere.

# 9. set f 1 (from:x7)
# 10. set d 2
# 11. set e 2 (from:x4)
# 12. set g d (from:x3)
# --- x2
# 20. jnz g -8 (to:x3)
# 21. sub d -1
# 22. set g d
# 23. sub g b
# 24. jnz g -13 (to:x4)
# --- x5
# 29. jnz g 2 (to:x6)
# 30. jnz 1 3 (to:EXIT)
# 31. sub b -17 (from:x6)
# 32. jnz 1 -23 (to:x7)

def puzzle2():
    b = 109300
    c = 126300
    d, e, f, g, h = 0

    # x2
    g = (g * e) - b

    if g == 0:
        f = 0

    e = e + 1
    g = e - b
    # x2

    # x5
    if f == 0:
        h = h + 1
    g = b - c
    # x5
    return h

# x3 jump removed

# 9. set f 1 (from:x7)
# 10. set d 2
# 11. set e 2 (from:x4)
# --- x3
# 21. sub d -1
# 22. set g d
# 23. sub g b
# 24. jnz g -13 (to:x4)
# --- x5
# 29. jnz g 2 (to:x6)
# 30. jnz 1 3 (to:EXIT)
# 31. sub b -17 (from:x6)
# 32. jnz 1 -23 (to:x7)

def puzzle2():
    b = 109300
    c = 126300
    d, e, f, g, h = 0

    # x3
    while True:
        g = (d * e) - b

        if g == 0:
            f = 0

        e = e + 1
        g = e - b
        if g == 0:
            break
    # x3

    # x5
    if f == 0:
        h = h + 1
    g = b - c
    # x5
    return h

# x4 jump removed

# 9. set f 1 (from:x7)
# --- x5
# 29. jnz g 2 (to:x6)
# 30. jnz 1 3 (to:EXIT)
# 31. sub b -17 (from:x6)
# 32. jnz 1 -23 (to:x7)

def puzzle2():
    b = 109300
    c = 126300
    d, e, f, g, h = 0

    # x5
    d = 2
    while True:
        e = 2
        while True:
            g = (d * e) - b

            if g == 0:
                f = 0

            e = e + 1
            g = e - b
            if g == 0:
                break
        d = d + 1
        g = d - b
        if g == 0:
            break

    if f == 0:
        h = h + 1
    g = b - c
    # x5
    return h

# all jumps removed, initial naive Python version finished.

def puzzle2():
    b = 109300
    c = 126300
    h = 0

    while True:
        f = 1
        d = 2
        while True:
            e = 2
            while True:
                g = (d * e) - b

                if g == 0:
                    f = 0

                e = e + 1
                g = e - b
                if g == 0:
                    break
            d = d + 1
            g = d - b
            if g == 0:
                break

        if f == 0:
            h = h + 1
        g = b - c
        if g == 0:
            break
        b = b + 17
    return h

# remove redundant `g` register

def puzzle2():
    b = 109300
    c = 126300
    h = 0

    while True:
        f = 1
        d = 2
        while True:
            e = 2
            while True:
                if (d * e) - b == 0:
                    f = 0
                e = e + 1
                if e - b == 0:
                    break
            d = d + 1
            if d - b == 0:
                break

        if f == 0:
            h = h + 1

        if b - c == 0:
            break
        b = b + 17
    return h


# remove c register, switch to range instead of infinite loop.

def puzzle2():
    h = 0

    for b in range(109300, 126300, 17):
        f = 1
        d = 2
        while True:
            e = 2
            while True:
                if (d * e) - b == 0:
                    f = 0
                e = e + 1
                if e - b == 0:
                    break
            d = d + 1
            if d - b == 0:
                break

        if f == 0:
            h = h + 1
    return h

#  remove innermost infinite loop & use range as well.

def puzzle2():
    h = 0

    for b in range(109300, 126300, 17):
        f = 1
        d = 2
        while True:
            for e in range(2, b):
                if (d * e) - b == 0:
                    f = 0
            d = d + 1
            if d - b == 0:
                break

        if f == 0:
            h = h + 1
    return h


#  remove next innermost infinite loop & use range as well.

def puzzle2():
    h = 0

    for b in range(109300, 126300, 17):
        f = 1
        for d in range(2, b):
            for e in range(2, b):
                if (d * e) - b == 0:
                    f = 0

        if f == 0:
            h = h + 1
    return h

# skip redundant cycles & simplify

def puzzle2():
    h = 0

    for b in range(109300, 126300, 17):
        found = False
        for d in range(2, b):
            for e in range(2, b):
                if d * e == b:
                    found = True
                    break
            if found:
                break

        if found:
            h += 1
    return h

# at this point I actually figured out, we're counting dividers. so ditch
# the innermost loop & `found` var as well, since they're redundant.

def puzzle2():
    h = 0

    for b in range(109300, 126300, 17):
        for d in range(2, b):
            if b % d == 0:
                h += 1
                break
    return h

# obviously, get fucked by an off-by-one error as the final insult.

def puzzle2():
    h = 0

    for b in range(109300, 126300 + 1, 17):
        for d in range(2, b):
            if b % d == 0:
                h += 1
                break
    return h

if __name__ == "__main__":
    print puzzle2()