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44 lines
No EOL
896 B
Ruby
44 lines
No EOL
896 B
Ruby
#The Fibonacci sequence is defined by the recurrence relation:
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# Fn = Fn−1 + Fn−2, where F1 = 1 and F2 = 1.
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#Hence the first 12 terms will be:
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#
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# F1 = 1
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# F2 = 1
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# F3 = 2
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# F4 = 3
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# F5 = 5
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# F7 = 13
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# F8 = 21
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# F6 = 8
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# F9 = 34
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# F10 = 55
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# F11 = 89
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# F12 = 144
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#
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#The 12th term, F12, is the first term to contain three digits.
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#What is the index of the first term in the Fibonacci sequence to contain 1000 digits?
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def solution(num_digits = 1000)
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#Fn = Fn−1 + Fn−2, where F1 = 1 and F2 = 1.
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resultn1 = 1
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resultn2 = 1
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result = 2
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index = 3
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value = true
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while value
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resultn2 = resultn1
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resultn1 = result
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if (resultn1 + resultn2).abs.digits.length < num_digits
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value = true
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else
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value = false
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end
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result = resultn1 + resultn2
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index += 1
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end
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res = index
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end
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answer = solution()
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p answer
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