My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2018/21
+103
+69
2018/day21.py
+69
2018/day21.py
···
1
+
import fileinput
2
+
3
+
4
+
def emulate(program, ip_reg):
5
+
"""
6
+
Emulate the program while watching register 1, as this program is a
7
+
PRNG that will terminate if regs[0] == regs[1] at instruction 28.
8
+
"""
9
+
pc = 0
10
+
regs = [0, 0, 0, 0, 0, 0]
11
+
12
+
seen = set()
13
+
first_halt = None
14
+
last_halt = None
15
+
16
+
while 0 <= pc < len(program):
17
+
cmd, a, b, c = program[pc]
18
+
regs[ip_reg] = pc
19
+
20
+
if cmd == 'addr': regs[c] = regs[a] + regs[b]
21
+
elif cmd == 'addi': regs[c] = regs[a] + b
22
+
elif cmd == 'mulr': regs[c] = regs[a] * regs[b]
23
+
elif cmd == 'muli': regs[c] = regs[a] * b
24
+
elif cmd == 'banr': regs[c] = regs[a] & regs[b]
25
+
elif cmd == 'bani': regs[c] = regs[a] & b
26
+
elif cmd == 'borr': regs[c] = regs[a] | regs[b]
27
+
elif cmd == 'bori': regs[c] = regs[a] | b
28
+
elif cmd == 'setr': regs[c] = regs[a]
29
+
elif cmd == 'seti': regs[c] = a
30
+
elif cmd == 'gtir': regs[c] = int(a > regs[b])
31
+
elif cmd == 'gtri': regs[c] = int(regs[a] > b)
32
+
elif cmd == 'gtrr': regs[c] = int(regs[a] > regs[b])
33
+
elif cmd == 'eqir': regs[c] = int(a == regs[b])
34
+
elif cmd == 'eqri': regs[c] = int(regs[a] == b)
35
+
elif cmd == 'eqrr': regs[c] = int(regs[a] == regs[b])
36
+
37
+
# This is where the program checks to break and halt, so
38
+
# take note of whatever value is in register 1.
39
+
if pc == 28:
40
+
if first_halt is None:
41
+
first_halt = regs[1]
42
+
elif regs[1] in seen:
43
+
break
44
+
else:
45
+
last_halt = regs[1]
46
+
seen.add(regs[1])
47
+
48
+
pc = regs[ip_reg]
49
+
pc += 1
50
+
51
+
return first_halt, last_halt
52
+
53
+
54
+
PROGRAM = []
55
+
IP = None
56
+
57
+
for line in fileinput.input():
58
+
parts = line.split()
59
+
60
+
if fileinput.isfirstline():
61
+
IP = int(parts[1])
62
+
else:
63
+
a, b, c = [int(x) for x in parts[1:4]]
64
+
PROGRAM.append((parts[0], a, b, c))
65
+
66
+
first_halt, last_halt = emulate(PROGRAM, IP)
67
+
68
+
print "Lowest value for register 0 with fewest cycles:", first_halt
69
+
print "Lowest value for register 0 with the most cycles:", last_halt
+32
2018/inputs/21.txt
+32
2018/inputs/21.txt
···
1
+
#ip 4
2
+
seti 123 0 1
3
+
bani 1 456 1
4
+
eqri 1 72 1
5
+
addr 1 4 4
6
+
seti 0 0 4
7
+
seti 0 3 1
8
+
bori 1 65536 5
9
+
seti 8586263 3 1
10
+
bani 5 255 2
11
+
addr 1 2 1
12
+
bani 1 16777215 1
13
+
muli 1 65899 1
14
+
bani 1 16777215 1
15
+
gtir 256 5 2
16
+
addr 2 4 4
17
+
addi 4 1 4
18
+
seti 27 8 4
19
+
seti 0 1 2
20
+
addi 2 1 3
21
+
muli 3 256 3
22
+
gtrr 3 5 3
23
+
addr 3 4 4
24
+
addi 4 1 4
25
+
seti 25 8 4
26
+
addi 2 1 2
27
+
seti 17 7 4
28
+
setr 2 0 5
29
+
seti 7 8 4
30
+
eqrr 1 0 2
31
+
addr 2 4 4
32
+
seti 5 4 4