60 lines
1.5 KiB
Python
60 lines
1.5 KiB
Python
#!/usr/bin/env python3
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# The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); so the first ten triangle numbers are:
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#
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# 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
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#
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# By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value.
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# For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a triangle number then we shall call the word a triangle word.
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#
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# Using p042_words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words,
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# how many are triangle words?
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import sys
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from projecteuler import timing
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def is_triang(n: int) -> bool:
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i = 1
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j = 1
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while j <= n:
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if n == j:
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return True
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i = i + 1
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j = j + i
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return False
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@timing
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def p042() -> None:
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try:
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with open('p042_words.txt', 'r', encoding='utf-8') as fp:
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words = list(fp.readline().replace('"', '').split(','))
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except FileNotFoundError:
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print('Error while opening file p042_words.txt')
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sys.exit(1)
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count = 0
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# For each word, calculate its value and check if it's a triangle number.
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for word in words:
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value = 0
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l = len(word)
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for j in range(l):
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value = value + ord(word[j]) - ord('A') + 1
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if is_triang(value):
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count = count + 1
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print('Project Euler, Problem 42')
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print(f'Answer: {count}')
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if __name__ == '__main__':
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p042()
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