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48 lines
1.4 KiB
Python
48 lines
1.4 KiB
Python
"""
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The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); so
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the first ten triangle numbers are:
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1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
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By converting each letter in a word to a number corresponding to its
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alphabetical position and adding these values we form a word value. For example,
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the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a
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triangle number then we shall call the word a triangle word.
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Using words.txt (right click and 'Save Link/Target As...'), a 16K text file
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containing nearly two-thousand common English words, how many are triangle
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words?
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"""
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import os
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# Precomputes a list of the 100 first triangular numbers
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TRIANGULAR_NUMBERS = [int(0.5 * n * (n + 1)) for n in range(1, 101)]
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def solution():
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"""
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Finds the amount of triangular words in the words file.
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>>> solution()
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162
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"""
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script_dir = os.path.dirname(os.path.realpath(__file__))
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wordsFilePath = os.path.join(script_dir, "words.txt")
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words = ""
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with open(wordsFilePath, "r") as f:
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words = f.readline()
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words = list(map(lambda word: word.strip('"'), words.strip("\r\n").split(",")))
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words = list(
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filter(
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lambda word: word in TRIANGULAR_NUMBERS,
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map(lambda word: sum(map(lambda x: ord(x) - 64, word)), words),
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)
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)
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return len(words)
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if __name__ == "__main__":
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print(solution())
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