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authorEgor Tensin <Egor.Tensin@gmail.com>2019-12-23 07:32:18 +0300
committerEgor Tensin <Egor.Tensin@gmail.com>2019-12-23 07:32:18 +0300
commit0d25b5d6957d76bab486e2279c99e130c19d5c31 (patch)
treec8c7d6fe4766470bda03e49a004afaa03c967b16 /algorithms/impl/heapsort.py
parentTravis: add badge to README (diff)
downloadsorting-algorithms-0d25b5d6957d76bab486e2279c99e130c19d5c31.tar.gz
sorting-algorithms-0d25b5d6957d76bab486e2279c99e130c19d5c31.zip
pylint/pep8 fixes
Diffstat (limited to 'algorithms/impl/heapsort.py')
-rw-r--r--algorithms/impl/heapsort.py11
1 files changed, 11 insertions, 0 deletions
diff --git a/algorithms/impl/heapsort.py b/algorithms/impl/heapsort.py
index bf9f464..81bea20 100644
--- a/algorithms/impl/heapsort.py
+++ b/algorithms/impl/heapsort.py
@@ -9,6 +9,7 @@ from ..algorithm import SortingAlgorithm
# Disclaimer: implemented in the most literate way.
+
def heapsort(xs):
_heapify(xs)
first, last = 0, len(xs) - 1
@@ -17,26 +18,32 @@ def heapsort(xs):
_siftdown(xs, first, end - 1)
return xs
+
# In a heap stored in a zero-based array,
# left_child = node * 2 + 1
# right_child = node * 2 + 2
# parent = (node - 1) // 2
+
def _get_parent(node):
return (node - 1) // 2
+
def _get_left_child(node):
return node * 2 + 1
+
def _get_right_child(node):
return node * 2 + 2
+
def _heapify(xs):
last = len(xs) - 1
first_parent, last_parent = 0, _get_parent(last)
for parent in range(last_parent, first_parent - 1, -1):
_siftdown(xs, parent, last)
+
def _siftdown(xs, start, end):
root = start
while True:
@@ -54,18 +61,22 @@ def _siftdown(xs, start, end):
else:
break
+
_ALGORITHMS = [
SortingAlgorithm('heapsort', 'Heapsort', heapsort),
]
+
def _parse_args(args=None):
if args is None:
args = sys.argv[1:]
return list(map(int, args))
+
def main(args=None):
xs = _parse_args(args)
print(heapsort(list(xs)))
+
if __name__ == '__main__':
main()