在 Python 中获取最大堆

# import the heapq module.
import heapq

# Max Heap With Numbers

# Create a list.
x = [5, 4, 3, 6, 8, 7, 2, 1]
# Print the list.
print(x)

# Multiply elements by -1.
x_inv = [-1*i for i in x]
print(x_inv)

# Make the heap.
heapq.heapify(x_inv)

# Pop the maximum value.
# RUN ONE LINE AT A TIME.
-1 * heapq.heappop(x_inv)
-1 * heapq.heappop(x_inv)
-1 * heapq.heappop(x_inv)

print(x)
[5, 4, 3, 6, 8, 7, 2, 1]

print(x_inv)
[-5, -4, -3, -6, -8, -7, -2, -1]

-1 * heapq.heappop(x_inv)
Out[8]: 8

-1 * heapq.heappop(x_inv)
Out[9]: 7

-1 * heapq.heappop(x_inv)
Out[10]: 6

# Max Heap With Tuples

# Make a list of tuples.
l = [(1, "A"), (5, "B"), (3, "C"), (7, "D"), (6.5, "E")]
# View the list.
l

# Create an empty list to hold modified tuples.
l_max = []

# Populate the list with modified tuples.
for i in range(len(l)):
    j = list(l[i])
    j[0] = -1* j[0]
    l_max.append(tuple(j))

# View the modified list.
l_max

# Create the min heap.
heapq.heapify(l_max)

# View the min-heap.
l_max

# Create a function that uses meappop and
# changes the number back to a positive value.
def maxpop(mh):
    l = list(heapq.heappop(mh))
    l[0] = -1*l[0]
    return tuple(l)

# Test the values popped by the maxpop.
# RUN ONE LINE AT A TIME.
maxpop(l_max)
maxpop(l_max)
maxpop(l_max)

l
Out[15]: [(1, 'A'), (5, 'B'), (3, 'C'), (7, 'D'), (6.5, 'E')]

l_max
Out[14]: [(-1, 'A'), (-5, 'B'), (-3, 'C'), (-7, 'D'), (-6.5, 'E')]

heapq.heapify(l_max)

l_max
Out[17]: [(-7, 'D'), (-6.5, 'E'), (-3, 'C'), (-5, 'B'), (-1, 'A')]

maxpop(l_max)
Out[19]: (7, 'D')

maxpop(l_max)
Out[20]: (6.5, 'E')

maxpop(l_max)
Out[21]: (5, 'B')