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+""" A node is a container which encapsulates any type of data.
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+ The node object also has a reference to the NODE preceding and following
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+ said object."""
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+class Node(object):
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+
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+ def __init__(self, data, prev, next):
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+ self.data = data
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+ self.prev = prev
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+ self.next = next
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+
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+ def getNext(self):
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+ if self.next is not None:
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+ return self.next
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+ print('There\'s nothing next, trying prev')
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+ if self.prev is not None:
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+ return self.prev
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+ print('There\s nothing before either, just this one')
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+ return self
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+
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+ def getPrev(self):
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+ if self.prev is not None:
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+ return self.prev
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+ print('There\'s nothing before, trying next')
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+ if self.next is not None:
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+ return self.next
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+ print('There\'s nothing next either, just this one')
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+ return self
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+
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+ def getData(self):
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+ return self.data
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+
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+""" A doubly-linked list implementation
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+ NOTE: the getters and setters return a reference to a Node object,
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+ inside which is the data you're probably looking for. If you want to
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+ access data, remember; after you call a get or find, use .data"""
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+class DoubleList(object):
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+
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+ head = None
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+ tail = None
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+ length = 0;
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+
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+ """ Add a node to the list """
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+ def append(self, data):
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+ new_node = Node(data, None, None)
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+ if self.head is None:
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+ self.head = self.tail = new_node
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+ else:
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+ new_node.prev = self.tail
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+ new_node.next = None
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+ self.tail.next = new_node
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+ self.tail = new_node
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+ self.length = self.length + 1
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+
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+ """ Find a node in the list, then remove it """
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+ def remove(self, node):
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+ current_node = self.head
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+
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+ while current_node is not None:
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+ if current_node == node:
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+ # if it's not the first element
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+ if current_node.prev is not None:
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+ current_node.prev.next = current_node.next
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+ current_node.next.prev = current_node.prev
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+ else:
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+ # otherwise we have no prev (it's None), head is the next one, and prev becomes None
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+ self.head = current_node.next
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+ current_node.next.prev = None
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+
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+ current_node = current_node.next
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+ self.length = self.length - 1
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+
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+ """ Display the contents of this list NOTE: Currently broken"""
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+ def show(self):
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+ print("Show list data:")
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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.data)
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+ current_node = current_node.next
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+ print("*"*50)
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+
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+ """ Find a node in the list by value comparison """
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+ def findNode(self, node_value):
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+ current_node = self.head
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+
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+ while current_node is not None:
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+ if current_node.data == node_value:
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+ return current_node
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+ current_node = current_node.next
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+
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+ """ Get a node by index position """
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+ def get(self, index):
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+ if index > self.length:
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+ return none
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+ elif index == 1:
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+ return self.head
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+ elif index == self.length:
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+ return self.tail
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+ else:
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+ current_node = self.head
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+ pos = 1
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+ while pos < index:
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+ current_node = current_node.next
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+ pos = pos + 1
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+ return current_node
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+
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+ """ Checks if a node is in this list """
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+ def contains(self, node):
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+ current_node = self.head
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+ while current_node is not None:
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+ if current_node == node:
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+ return true
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+ current_node = current_node.next
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+ return false
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+
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+ """ Get the length of this list """
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+ def getLength(self):
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+ return self.length
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+
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+ """ Get the head of this list """
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+ def getHead(self): # get head (;
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+ return self.head
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+
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+ """ Get the tail of this list """
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+ def getTail(self):
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+ return self.tail
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