52 lines
760 B
Ruby
52 lines
760 B
Ruby
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def parse_words
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file = File.open('p042_words.txt')
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words = file.read.delete('"').split(',')
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file.close
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words
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end
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def perfect_square?(n)
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Math.sqrt(n) % 1 == 0
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end
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def triangle_number?(n)
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perfect_square?((8 * n) + 1)
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end
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ALPHABET = {
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'A' => 1,
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'B' => 2,
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'C' => 3,
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'D' => 4,
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'E' => 5,
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'F' => 6,
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'G' => 7,
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'H' => 8,
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'I' => 9,
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'J' => 10,
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'K' => 11,
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'L' => 12,
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'M' => 13,
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'N' => 14,
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'O' => 15,
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'P' => 16,
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'Q' => 17,
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'R' => 18,
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'S' => 19,
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'T' => 20,
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'U' => 21,
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'V' => 22,
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'W' => 23,
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'X' => 24,
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'Y' => 25,
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'Z' => 26
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}
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def triangle_word?(word)
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triangle_number?(word.split('').map { |c| ALPHABET[c] }.inject(:+))
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end
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def count_triangle_words
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parse_words.select { |w| triangle_word?(w) }.count
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end
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