My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2017/10
+52
+49
2017/day10.py
+49
2017/day10.py
···
1
+
import fileinput
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3
+
4
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def knot_hash(elems, lengths, pos=0, skip=0):
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for l in lengths:
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for i in range(l // 2):
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x = (pos + i) % len(elems)
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y = (pos + l - i - 1) % len(elems)
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elems[x], elems[y] = elems[y], elems[x]
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pos = pos + l + skip % len(elems)
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skip += 1
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return elems, pos, skip
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# Read puzzle input
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line = fileinput.input()[0].strip()
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# Part 1
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try:
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lengths = [int(x) for x in line.split(',')]
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elems = knot_hash(range(0, 256), lengths)[0]
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print "Product of first two items in list:", elems[0] * elems[1]
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except ValueError:
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print "Skipping part 1 (can't parse puzzle input into ints)"
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# Part 2
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lengths = [ord(x) for x in line] + [17, 31, 73, 47, 23]
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elems = range(0, 256)
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pos = 0
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skip = 0
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# Perform 64 rounds of Knot Hash
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for _ in range(64):
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elems, pos, skip = knot_hash(elems, lengths, pos, skip)
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# Convert from sparse hash to dense hash
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sparse = elems
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dense = []
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for i in range(16):
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res = 0
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for j in range(0, 16):
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res ^= sparse[(i * 16) + j]
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dense.append(res)
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print "Knot Hash of puzzle input:", ''.join(hex(x)[2:] for x in dense)
+1
2017/inputs/10.txt
+1
2017/inputs/10.txt
···
1
+
189,1,111,246,254,2,0,120,215,93,255,50,84,15,94,62