def max_heapify(A, i):
"""Given array A and index i, max_heapify assumes left(i) and right(i) are max-heaps, but A[i] might be smaller than its children."""
L = left(i)
R = right(i)
if L <= len(A) - 1 and A[L] > A[i]: # assume len(A) is A.heap_size
largest = L
else:
largest = i
if R <= len(A) - 1 and A[R] > A[largest]:
largest = R
if largest != i:
A[i], A[largest] = A[largest], A[i]
max_heapify(A, largest)
def minheapify(self, A, i):
'''
保持堆:使某一个结点i成为最小堆(其子树本身已经为最小堆)
'''
l = heap.left(i)
r = heap.right(i)
minest = 0
if l <= heap.heapsize(A) and A[l] <= A[i]:
minest = l
else:
minest = i
if r <= heap.heapsize(A) and A[r] <= A[minest]:
minest = r
if minest != i:
A[i], A[minest] = A[minest], A[i]
self.minheapify(A, minest)
return A
def maxheapify(self, A, i):
'''
保持堆:使某一个结点i成为最大堆(其子树本身已经为最大堆)
'''
l = heap.left(i)
r = heap.right(i)
largest = 0
if l <= heap.heapsize(A) and A[l] >= A[i]:
largest = l
else:
largest = i
if r <= heap.heapsize(A) and A[r] >= A[largest]:
largest = r
if largest != i:
A[i], A[largest] = A[largest], A[i]
self.maxheapify(A, largest)
return A
def maxheapify_quick(self, A, i):
'''
保持堆:使某一个结点i成为最大堆(其子树本身已经为最大堆)
'''
count = len(A)
largest = count
while largest != i:
l = heap.left(i)
r = heap.right(i)
if l <= heap.heapsize(A) and A[l] >= A[i]:
largest = l
else:
largest = i
if r <= heap.heapsize(A) and A[r] >= A[largest]:
largest = r
if largest != i:
A[i], A[largest] = A[largest], A[i]
i, largest = largest, count
return A
def test_left(self):
self.assertEqual(5, left(2))
self.assertEqual(7, left(3))