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Remove extra len calls in doubly-linked-list's methods #8600

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Merged
merged 1 commit into from
Apr 1, 2023
Merged

Remove extra len calls in doubly-linked-list's methods #8600

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14 changes: 9 additions & 5 deletions data_structures/linked_list/doubly_linked_list.py
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Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,9 @@ def insert_at_nth(self, index: int, data):
....
IndexError: list index out of range
"""
if not 0 <= index <= len(self):
length = len(self)

if not 0 <= index <= length:
raise IndexError("list index out of range")
new_node = Node(data)
if self.head is None:
Expand All @@ -90,7 +92,7 @@ def insert_at_nth(self, index: int, data):
self.head.previous = new_node
new_node.next = self.head
self.head = new_node
elif index == len(self):
elif index == length:
self.tail.next = new_node
new_node.previous = self.tail
self.tail = new_node
Expand Down Expand Up @@ -131,15 +133,17 @@ def delete_at_nth(self, index: int):
....
IndexError: list index out of range
"""
if not 0 <= index <= len(self) - 1:
length = len(self)

if not 0 <= index <= length - 1:
raise IndexError("list index out of range")
delete_node = self.head # default first node
if len(self) == 1:
if length == 1:
self.head = self.tail = None
elif index == 0:
self.head = self.head.next
self.head.previous = None
elif index == len(self) - 1:
elif index == length - 1:
delete_node = self.tail
self.tail = self.tail.previous
self.tail.next = None
Expand Down