London | 25-SDC-July | Andrei Filippov | Sprint 2 | Implement a linked list in Python #28
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| class LinkedList: | ||
| def __init__(self): | ||
| self.head = None | ||
| self.tail = None | ||
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| def push_head(self, element): | ||
| node = Node(element) | ||
| if self.head and self.tail: | ||
| node.next = self.head | ||
| self.head.previous = node | ||
| self.head = node | ||
| elif not self.head and not self.tail: | ||
|
There was a problem hiding this comment. This line could probably be simplified. |
||
| self.head = node | ||
| self.tail = node | ||
| return node | ||
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| def pop_tail(self): | ||
| node = self.tail | ||
| if self.tail is not self.head: | ||
| self.tail = node.previous | ||
| node.previous.next = None | ||
| node.previous = None | ||
| else: | ||
| self.head = None | ||
| self.tail = None | ||
| return node.value | ||
|
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| def remove(self, node): | ||
| if self.head != node and self.tail != node: | ||
| node.previous.next = node.next | ||
| node.next.previous = node.previous | ||
| node.previous, node.next = None, None | ||
| elif self.head == node and self.tail != node: | ||
| node.next.previous = None | ||
| self.head = node.next | ||
| node.previous, node.next = None, None | ||
| elif self.head != node and self.tail == node: | ||
| node.previous.next = None | ||
| self.tail = node.previous | ||
| node.previous, node.next = None, None | ||
| elif self.head == node and self.tail == node: | ||
|
Comment on lines
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There was a problem hiding this comment. The conditions can be simplified (reduce the amount of checking needed) as: if self.head == node:
if self.tail == node:
# Case 1: head == node, tail == node
else:
# Case 2: head == node, tail != node
else;
if self.tail == node:
# Case 3: head != node, tail == node
else:
# Case 4: head != node, tail != nodeOnly two comparisons needed. |
||
| self.head = None | ||
| self.tail = None | ||
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| class Node: | ||
| def __init__(self, value): | ||
| self.value = value | ||
| self.previous = None | ||
| self.next = None | ||
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Is it necessary to check also
self.tail?