My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2016/23
+125
+97
2016/day23.py
+97
2016/day23.py
···
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import fileinput
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from copy import deepcopy
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def reg_or_val(regs, x):
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try:
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return int(x)
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except ValueError:
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return regs[x]
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def emulate(program, a=0, b=0, c=0, d=0):
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pc = 0
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regs = {'a': a, 'b': b, 'c': c, 'd': d}
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# Toggling instructions modifes the program, so operate on a copy instead.
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program = deepcopy(program)
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while True:
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if pc >= len(program):
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return regs
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cmd, x, y = program[pc]
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if cmd == 'cpy':
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# Subroutines that look like this perform multiplication:
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# cpy b c
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# inc a
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# dec c
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# jnz c -2
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# dec d
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# jnz d -5
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# Perform a lookahead and optimize it by doing the following:
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# - Set a to b*d
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# - Set c and d to 0.
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# - Move forward 5 instructions.
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next_cmds, next_regs = zip(*program[pc+1:pc+5])[0:2]
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if x.isalpha() and next_cmds == ('inc', 'dec', 'jnz', 'dec'):
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a, _, c, d = next_regs
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regs[a] = regs[x] * regs[d]
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regs[c] = 0
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regs[d] = 0
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pc += 5
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continue
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# Ignore copy instructions that try to copy a value into an
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# immediate value (occurs when toggling instructions).
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if y.isalpha():
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regs[y] = reg_or_val(regs, x)
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elif cmd == 'inc':
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regs[x] += 1
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elif cmd == 'dec':
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regs[x] -= 1
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elif cmd == 'jnz':
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x = reg_or_val(regs, x)
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if x != 0:
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pc += reg_or_val(regs, y)
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continue
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elif cmd == 'tgl':
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x = reg_or_val(regs, x)
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to_toggle = pc + x
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try:
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cng, nx, ny = program[to_toggle]
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except:
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pc += 1
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continue
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if ny == 'null':
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if cng == 'inc':
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program[to_toggle][0] = 'dec'
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else:
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program[to_toggle][0] = 'inc'
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else:
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if cng == 'jnz':
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program[to_toggle][0] = 'cpy'
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else:
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program[to_toggle][0] = 'jnz'
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pc += 1
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PROGRAM = []
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for line in fileinput.input():
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# Add null argument to pad inc/dec instructions
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instruction = line + ' null'
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PROGRAM.append(instruction.split()[:3])
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print "Value to send to safe:", emulate(PROGRAM, a=7)['a']
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print "Actual value for safe:", emulate(PROGRAM, a=12)['a']
+26
2016/inputs/23.txt
+26
2016/inputs/23.txt
···
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cpy a b
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dec b
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cpy a d
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cpy 0 a
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cpy b c
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inc a
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dec c
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jnz c -2
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dec d
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jnz d -5
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dec b
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cpy b c
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cpy c d
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dec d
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inc c
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jnz d -2
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tgl c
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cpy -16 c
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jnz 1 c
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cpy 94 c
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jnz 82 d
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inc a
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inc d
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jnz d -2
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inc c
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jnz c -5