My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Update 2015/day20.py
Cache previous calls to factors() function.
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-12
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2015/day20.py
+19
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2015/day20.py
···
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import fileinput
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PRESENTS = int(fileinput.input()[0].strip())
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CACHE = {}
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def factors(n):
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return set(x for tup in ([i, n//i]
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for i in range(1, int(n**0.5)+1) if n % i == 0) for x in tup)
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if n in CACHE:
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return CACHE[n]
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CACHE[n] = set()
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for i in range(1, int(n**0.5) + 1):
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if n % i == 0:
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CACHE[n] |= set([i, n//i])
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return CACHE[n]
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house = 1
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while True:
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if sum(factors(house)) * 10 >= PRESENTS:
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print "Lowest house number #1:", house
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break
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while sum(factors(house)) * 10 < PRESENTS:
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house += 1
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print "Lowest house number #1:", house
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house = 1
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while sum(x for x in factors(house) if (x * 50 >= house)) * 11 < PRESENTS:
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house += 1
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while True:
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if sum(x for x in factors(house) if (x * 50 >= house)) * 11 >= PRESENTS:
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print "Lowest house number #2:", house
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break
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house += 1
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print "Lowest house number #2:", house