My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add solution for 2016/17
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2016/day17.py
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2016/day17.py
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import fileinput
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from hashlib import md5
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from itertools import compress
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DIRS = {
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'U': (0, -1),
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'D': (0, 1),
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'L': (-1, 0),
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'R': (1, 0),
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}
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def open_doors(digest):
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"""Returns a 4-tuple of booleans representing whether doors UDLR are open."""
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return [x in 'bcdef' for x in digest[:4]]
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def pathfind(salt):
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horizon = [(0, 0, '')]
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while horizon:
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x, y, path = horizon.pop(0)
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digest = md5(salt + path).hexdigest()
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for door in compress('UDLR', open_doors(digest)):
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dx, dy = DIRS[door]
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nx, ny = x + dx, y + dy
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if (0 <= nx < 4) and (0 <= ny < 4):
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if nx == 3 and ny == 3:
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yield path + door
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else:
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horizon.append((nx, ny, path + door))
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if __name__ == '__main__':
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salt = fileinput.input()[0].strip()
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paths = sorted(pathfind(salt), key=len)
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print 'Shortest path:', paths[0]
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print 'Longest path length:', len(paths[-1])
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2016/input17.txt
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2016/input17.txt
···
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