My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2023/19
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+109
2023/day19.py
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2023/day19.py
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import copy
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import fileinput
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from utils import mul
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# Parse problem input.
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RULES = {}
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WORKFLOWS = []
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for line in fileinput.input():
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line = line.strip()
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if line.startswith('{'):
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WORKFLOWS.append([x for x in line[1:-1].split(',')])
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elif line.endswith('}'):
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name, rest = line.split('{')
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rules = []
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for r in rest[:-1].split(','):
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if all(x.isalpha() for x in r):
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rules.append(r)
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else:
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a, b, cond = r[0], r[1], r[2:]
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cond, out = cond.split(':')
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rules.append((a, b, int(cond), out))
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RULES[name] = rules
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# Solve part 1.
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part_1 = 0
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for wf in WORKFLOWS:
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regs = {}
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for state in wf:
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reg, val = state.split('=')
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regs[reg] = int(val)
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curr = 'in'
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while curr not in ('A', 'R'):
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for rule in RULES[curr]:
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if type(rule) == str:
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curr = rule
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break
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reg, cond, val, next_rule = rule
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if cond == '<':
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if regs[reg] < val:
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curr = next_rule
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break
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elif cond == '>':
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if regs[reg] > val:
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curr = next_rule
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break
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if curr == 'A':
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part_1 += sum(regs.values())
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print("Part 1:", part_1)
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# Solve part 2.
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INITIAL_HYPERCUBE = {k: [1, 4000] for k in 'xmas'}
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horizon = [('in', INITIAL_HYPERCUBE)]
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ACCEPTED = []
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while horizon:
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curr, intervals = horizon.pop()
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if curr == 'A':
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ACCEPTED.append(intervals)
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continue
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elif curr == 'R':
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continue
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for rule in RULES[curr]:
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if type(rule) == str:
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horizon.append((rule, intervals))
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break
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reg, cond, val, next_rule = rule
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if cond == '<':
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if intervals[reg][0] >= val:
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continue
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curr_bound = intervals[reg][1]
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new_intervals = copy.deepcopy(intervals)
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new_intervals[reg][1] = min(val - 1, curr_bound)
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horizon.append((next_rule, copy.deepcopy(new_intervals)))
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# Propagate the inverse state to the next case in the rule.
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curr_bound = intervals[reg][0]
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inverse_intervals = copy.deepcopy(intervals)
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inverse_intervals[reg][0] = max(val, curr_bound)
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intervals = inverse_intervals
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elif cond == '>':
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if intervals[reg][1] <= val:
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continue
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curr_bound = intervals[reg][0]
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new_intervals = copy.deepcopy(intervals)
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new_intervals[reg][0] = max(val + 1, curr_bound)
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horizon.append((next_rule, copy.deepcopy(new_intervals)))
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# Propagate the inverse state to the next case in the rule.
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curr_bound = intervals[reg][1]
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inverse_intervals = copy.deepcopy(intervals)
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inverse_intervals[reg][1] = min(val, curr_bound)
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intervals = inverse_intervals
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print("Part 2:", sum(mul(b - a + 1 for a, b in interval.values()) for interval in ACCEPTED))