My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Update day23.py
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2016/day23.py
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2016/day23.py
···
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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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while pc < len(program):
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cmd, x, y = program[pc]
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if cmd == 'cpy':
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# The following instructions simply perform multiplication:
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# The following set of instructions performs 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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#
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# Perform a peephole optimization 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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# - Advance the PC by 5 instructions.
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# - Advance the PC by 6 to jump past the 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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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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pc += 6
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continue
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# Ignore copy instructions that try to copy a value into an
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# Ignore cpy 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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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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i = pc + reg_or_val(regs, 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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ncmd, nx, ny = program[i]
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except IndexError:
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pass
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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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if ny == 'null':
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program[i][0] = 'dec' if ncmd == 'inc' else 'inc'
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else:
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program[to_toggle][0] = 'jnz'
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program[i][0] = 'cpy' if ncmd == 'jnz' else 'jnz'
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pc += 1
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return regs
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PROGRAM = []