Python/data_structures/heap/heap.py
Christian Clauss 9b95e4f662
Pyupgrade to python3.8 (#3616)
* Upgrade to Python 3.8 syntax

* updating DIRECTORY.md

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-10-21 12:46:14 +02:00

136 lines
3.4 KiB
Python

#!/usr/bin/python3
class Heap:
"""
>>> unsorted = [103, 9, 1, 7, 11, 15, 25, 201, 209, 107, 5]
>>> h = Heap()
>>> h.build_heap(unsorted)
>>> h.display()
[209, 201, 25, 103, 107, 15, 1, 9, 7, 11, 5]
>>>
>>> h.get_max()
209
>>> h.display()
[201, 107, 25, 103, 11, 15, 1, 9, 7, 5]
>>>
>>> h.insert(100)
>>> h.display()
[201, 107, 25, 103, 100, 15, 1, 9, 7, 5, 11]
>>>
>>> h.heap_sort()
>>> h.display()
[1, 5, 7, 9, 11, 15, 25, 100, 103, 107, 201]
>>>
"""
def __init__(self):
self.h = []
self.curr_size = 0
def get_left_child_index(self, i):
left_child_index = 2 * i + 1
if left_child_index < self.curr_size:
return left_child_index
return None
def get_right_child(self, i):
right_child_index = 2 * i + 2
if right_child_index < self.curr_size:
return right_child_index
return None
def max_heapify(self, index):
if index < self.curr_size:
largest = index
lc = self.get_left_child_index(index)
rc = self.get_right_child(index)
if lc is not None and self.h[lc] > self.h[largest]:
largest = lc
if rc is not None and self.h[rc] > self.h[largest]:
largest = rc
if largest != index:
self.h[largest], self.h[index] = self.h[index], self.h[largest]
self.max_heapify(largest)
def build_heap(self, collection):
self.curr_size = len(collection)
self.h = list(collection)
if self.curr_size <= 1:
return
for i in range(self.curr_size // 2 - 1, -1, -1):
self.max_heapify(i)
def get_max(self):
if self.curr_size >= 2:
me = self.h[0]
self.h[0] = self.h.pop(-1)
self.curr_size -= 1
self.max_heapify(0)
return me
elif self.curr_size == 1:
self.curr_size -= 1
return self.h.pop(-1)
return None
def heap_sort(self):
size = self.curr_size
for j in range(size - 1, 0, -1):
self.h[0], self.h[j] = self.h[j], self.h[0]
self.curr_size -= 1
self.max_heapify(0)
self.curr_size = size
def insert(self, data):
self.h.append(data)
curr = (self.curr_size - 1) // 2
self.curr_size += 1
while curr >= 0:
self.max_heapify(curr)
curr = (curr - 1) // 2
def display(self):
print(self.h)
def main():
for unsorted in [
[],
[0],
[2],
[3, 5],
[5, 3],
[5, 5],
[0, 0, 0, 0],
[1, 1, 1, 1],
[2, 2, 3, 5],
[0, 2, 2, 3, 5],
[2, 5, 3, 0, 2, 3, 0, 3],
[6, 1, 2, 7, 9, 3, 4, 5, 10, 8],
[103, 9, 1, 7, 11, 15, 25, 201, 209, 107, 5],
[-45, -2, -5],
]:
print("source unsorted list: %s" % unsorted)
h = Heap()
h.build_heap(unsorted)
print("after build heap: ", end=" ")
h.display()
print("max value: %s" % h.get_max())
print("delete max value: ", end=" ")
h.display()
h.insert(100)
print("after insert new value 100: ", end=" ")
h.display()
h.heap_sort()
print("heap sort: ", end=" ")
h.display()
print()
if __name__ == "__main__":
main()