72 lines
1.9 KiB
Python
72 lines
1.9 KiB
Python
# Solution to 2026.01.28 homework
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class Node:
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prev_node: "Node | None" = None
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next_node: "Node | None" = None
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def __init__(self, value) -> None:
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self.value = value
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class LinkedList:
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head: "Node | None" = None
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tail: "Node | None" = None
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def append(self, thing):
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if self.head==None:
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self.head=Node(value=thing)
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self.tail=self.head
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return
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if self.tail is not None:
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self.tail.next_node=Node(value=thing)
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if self.tail.next_node is not None:
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self.tail.next_node.prev_node = self.tail
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self.tail=self.tail.next_node
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def prepend(self, thing):
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previous_head = self.head
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self.head = Node(value=thing)
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self.head.next_node = previous_head
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if previous_head is not None:
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previous_head.prev_node = self.head
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def insert(self, thing, index):
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current_node = self.head
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if current_node is None:
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self.append(thing)
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return
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if index == 0:
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self.prepend(thing)
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return
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for _ in range(1, index):
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if current_node is not None:
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current_node = current_node.next_node
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if current_node is None:
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raise IndexError
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prev_next = current_node.next_node
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current_node.next_node = Node(thing)
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current_node.next_node.prev_node = current_node
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current_node.next_node.next_node = prev_next
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def print_list(self):
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current_node = self.head
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while current_node is not None:
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print(current_node.value)
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current_node = current_node.next_node
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example_list = LinkedList()
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example_list.append("first")
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example_list.append("second")
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example_list.append("fourth")
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example_list.insert("third", 2)
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example_list.insert("zero", 0)
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example_list.insert("last", 5)
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example_list.print_list()
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