59 lines
1.2 KiB
Julia
59 lines
1.2 KiB
Julia
#=
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Created on 21 Jul 2021
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@author: David Doblas Jiménez
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@email: daviddoji@pm.me
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Solution for Problem 012 of Project Euler
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https://projecteuler.net/problem=12
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=#
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using BenchmarkTools
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function num_divisors(number::Int64)
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res = isqrt(number)
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return 2 * count(number % i == 0 for i = 1:res) - (res^2 == number)
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end
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function Problem012()
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#=
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The sequence of triangle numbers is generated by adding the natural
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numbers. So the 7th triangle number would be:
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1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.
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The first ten terms would be:
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1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
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Let us list the factors of the first seven triangle numbers:
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1: 1
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3: 1,3
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6: 1,2,3,6
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10: 1,2,5,10
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15: 1,3,5,15
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21: 1,3,7,21
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28: 1,2,4,7,14,28
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We can see that 28 is the first triangle number to have over five divisors.
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What is the value of the first triangle number to have over five hundred
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divisors?
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=#
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ans = 0
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for number in Iterators.countfrom(1)
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ans += number
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if num_divisors(ans) > 500
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return ans
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end
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end
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end
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println("Took:")
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@btime Problem012()
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println("")
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println("Result for Problem $(lpad(12, 3, "0")): ", Problem012())
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