72 lines
2.0 KiB
Python
72 lines
2.0 KiB
Python
# Copyright 2016 Mirantis, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import math
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class BaseSequence(object):
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def __init__(self, n):
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self.n = n
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self.n_current = 0
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self.current = 1
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self.previous = 0
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def __iter__(self):
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return self
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def next(self):
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self.previous = self.current
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self.current += 1
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return self.current
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class CrossSumInequalitySequence(BaseSequence):
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"""An implementaion of a sequence from 1 to n
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https://oeis.org/A002620
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http://math.stackexchange.com/a/1596812/301008
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"""
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def next(self):
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if self.n_current >= self.n:
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raise StopIteration
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else:
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self.previous = int(math.floor((self.current + 1) / 2.0) *
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math.floor((self.current + 2) / 2.0))
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self.n_current += 1
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self.current += 1
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return self.previous
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class FibonacciSequence(BaseSequence):
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"""Generates fibinacci sequence
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Iterator over a sequence of Fibonacci numbers with n elements from 1 to n.
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"""
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def __init__(self, n):
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super(FibonacciSequence, self).__init__(n)
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self.previous = 0
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self.current = 1
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def next(self):
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if self.n_current > self.n:
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raise StopIteration
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else:
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self.n_current += 1
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self.previous, self.current = \
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self.current, self.current + self.previous
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return self.current
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