My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2021/{08,09}
+101
-19
+42
-19
2021/day08.py
+42
-19
2021/day08.py
···
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1
import fileinput
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-
from string import maketrans
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-
from itertools import permutations
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from collections import Counter
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4
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UNIQUES = {
···
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9: 'abcdfg',
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}
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-
SEGMENTS_MAP = {v: str(k) for k, v in DIGIT_MAP.items()}
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REVERSE_MAP = {v: k for k, v in DIGIT_MAP.items()}
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VALID_SEGMENTS = set(v for v in DIGIT_MAP.values())
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# a/c and d/g can both be diambiguated by 4,
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# who has a unique segument count, and also
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# contains c & d but not a & g.
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SEGMENT_FREQ = {
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# 'a': 8,
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'b': 6,
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# 'c': 8,
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# 'd': 7,
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'e': 4,
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'f': 9,
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# 'g': 7,
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}
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ALL_SEGMENTS = 'abcdefg'
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REVERSE_FREQ = {v: k for k, v in SEGMENT_FREQ.items()}
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part_1 = 0
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part_2 = 0
···
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part_1 += 1
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# Solve part 2
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for perm in permutations('abcdefg', 7):
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table = maketrans(ALL_SEGMENTS, perm)
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for word in input.split():
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if len(word) == 4:
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four_segments = word
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frequencies = Counter(input.replace(' ', ''))
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print frequencies.most_common()
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# break
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for word in input.split():
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new_word = word.translate(table)
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new_word = ''.join(sorted(new_word))
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mapping = {}
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for segment, count in frequencies.most_common():
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if count in REVERSE_FREQ:
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mapping[segment] = REVERSE_FREQ[count]
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elif count == 7:
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if segment in four_segments:
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mapping[segment] = 'd'
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else:
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mapping[segment] = 'g'
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elif count == 8:
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if segment in four_segments:
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mapping[segment] = 'c'
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else:
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mapping[segment] = 'a'
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if new_word not in VALID_SEGMENTS:
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break
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else:
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ans = ''
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for word in output.split():
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new_word = word.translate(table)
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new_word = ''.join(sorted(new_word))
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ans += SEGMENTS_MAP[new_word]
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code = ''
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for word in output.split():
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new_word = ''.join(sorted(mapping[l] for l in word))
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code += str(REVERSE_MAP[new_word])
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part_2 += int(ans)
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part_2 += int(code)
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print "Part 1:", part_1
+59
2021/day09.py
+59
2021/day09.py
···
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+
import fileinput
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from collections import Counter, defaultdict, deque, namedtuple # NOQA
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from utils import Point, mul
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# Read in problem input.
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WIDTH = HEIGHT = 0
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BOARD = {}
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for y, line in enumerate(fileinput.input()):
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line = line.strip()
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for x, c in enumerate(line):
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BOARD[Point(x, y)] = int(c)
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WIDTH = x + 1
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HEIGHT = y + 1
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LOW_POINTS = set()
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part_1 = 0
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# Solve part 1.
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for y in range(HEIGHT):
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for x in range(WIDTH):
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p = Point(x, y)
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val = BOARD[p]
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for n in p.neighbours_4():
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if n in BOARD:
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if BOARD[n] <= val:
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break
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else:
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LOW_POINTS.add(p)
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part_1 += (val + 1)
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print "Part 1:", part_1
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# Solve part 2.
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def compute_basin_size(board, start):
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"""Return the set of all explored points from a given point."""
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seen = set()
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def _dfs(node):
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val = board[node]
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seen.add(node)
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for n in node.neighbours_4():
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if n in board and n not in seen:
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if val <= board[n] and board[n] != 9:
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_dfs(n)
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_dfs(start)
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return len(seen)
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BASIN_SIZES = {}
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for p in LOW_POINTS:
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BASIN_SIZES[p] = compute_basin_size(BOARD, p)
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print "Part 2:", mul(sorted(BASIN_SIZES.values(), reverse=True)[:3])
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