59 lines
1.2 KiB
Python
59 lines
1.2 KiB
Python
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class FibonacciIterator(object):
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def __init__(self, max_n):
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self._precalculated = {0: 1, 1: 1, 2: 2, 3: 3, 4: 5}
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self._biggest = 4
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self._max_n = max_n
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self._i = 0
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def get_biggest_pair(self):
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return ((self._biggest - 1, self._precalculated[self._biggest - 1])
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, (self._biggest, self._precalculated[self._biggest]))
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def fibonacci_element(self, n):
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if(not isinstance(n, int)):
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raise TypeError("n must be integer")
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if(0 <= n <= self._biggest):
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return self._precalculated[n]
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(n_start_minus_one, b), (n_start, a) = self.get_biggest_pair()
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for i in range(n_start, n):
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swp = a
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a += b
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b = swp
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self._precalculated[n] = a
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self._biggest = n
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return a
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def __contains__(self, n):
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if(n > self._max_n):
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raise IndexError("{} > max_n({})".format(n, self._max_n))
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return n <= self._biggest
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def __getitem__(self, n):
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if(n > self._max_n):
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raise IndexError("{} > max_n({})".format(n, self._max_n))
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return self.fibonacci_element(n)
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def __iter__(self):
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self._i = -1
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return self
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def __next__(self):
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if(self._i > self._max_n):
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raise StopIteration()
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self._i += 1
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return self.fibonacci_element(self._i)
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if( __name__ == "__main__"):
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i = FibonacciIterator(20)
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for j in i:
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print(j)
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print(15 in i)
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print(i[14])
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