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https://github.com/autistic-symposium/master-algorithms-py.git
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50 lines
1.3 KiB
Python
50 lines
1.3 KiB
Python
#!/usr/bin/env python
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__author__ = "bt3"
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class Heapify(object):
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def __init__(self, data=None):
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self.data = data or []
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for i in range(len(data)//2, -1, -1):
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self.__max_heapify__(i)
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def __repr__(self):
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return '{}'.format(self.data)
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def parent(self, i):
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return i >> 1
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def left_child(self, i):
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return (i << 1) + 1
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def right_child(self, i):
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return (i << 1) + 2 # +2 instead of +1 because it's 0-indexed.
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def __max_heapify__(self, i):
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largest = i
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left = self.left_child(i)
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right = self.right_child(i)
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n = len(self.data)
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largest = (left < n and self.data[left] > self.data[i]) and left or i
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largest = (right < n and self.data[right] > self.data[largest]) and right or largest
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if i is not largest:
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self.data[i], self.data[largest] = self.data[largest], self.data[i]
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self.__max_heapify__(largest)
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def extract_max(self):
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n = len(self.data)
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max_element = self.data[0]
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self.data[0] = self.data[n - 1]
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self.data = self.data[:n - 1]
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self.__max_heapify__(0)
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return max_element
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def test_Heapify():
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l1 = [3, 2, 5, 1, 7, 8, 2]
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h = Heapify(l1)
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assert(h.extract_max() == 8)
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if __name__ == '__main__':
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test_Heapify()
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