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Merge pull request #12 from nickolasteixeira/chapter2
remove duplicate nodes, singly linked list
2 parents de29f3b + 8523aac commit dd40249

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‎Python/chapter02/2.1 - Remove Dups/Nick.py

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#!/usr/bin/python3
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import unittest
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class Node:
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def __init__(self, data, next=None):
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self.data = data
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self.next = next
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def __str__(self):
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return str(self.data)
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class SinglyLinkedList:
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def __init__(self):
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self.head = None
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self.size = 0
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def insertHead(self, data):
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print('Inserting head!----->', data)
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n = Node(data)
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temp = self.head
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self.head = n
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self.head.next = temp
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def addNode(self, data):
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if not self.head:
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n = Node(data)
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self.head = n
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else:
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n = self.head
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while (n.next):
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n = n.next
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print('New Node added ---->', data)
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new_node = Node(data)
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n.next = new_node
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def removeDuplicates(self):
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print('Removing Duplicates.')
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temp = self.head
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nums = set()
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while temp.next:
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nums.add(temp.data)
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if temp.next.data in nums:
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temp.next = temp.next.next
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temp = temp.next
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print('Duplicates Removed!---------')
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def removeDuplicatesNoBuffer(self):
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print('Removing Duplicates - No buffer')
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temp = self.head
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while temp.next:
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second = temp
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while second.next:
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if second.data == second.next.data:
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second.next = second.next.next
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second = second.next
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temp = temp.next
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print('Duplicates Removed!----------')
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def printList(self):
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n = self.head
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print('Printing Singly Linked List')
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while(n):
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print(n)
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n = n.next
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class Test(unittest.TestCase):
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@classmethod
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def setUpClass(cls):
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cls.link = SinglyLinkedList()
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cls.link.addNode(-1)
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cls.link.addNode(-1)
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cls.link.addNode(4)
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cls.link.addNode(3)
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cls.link.addNode(4)
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cls.link.addNode(1)
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cls.link.addNode(20)
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cls.link.addNode(4)
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cls.link.addNode(4)
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@classmethod
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def tearDownClass(cls):
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print('---Teardown successful---')
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def test1(self):
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self.link.printList()
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def test2(self):
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self.link.removeDuplicates()
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self.link.printList()
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def test3(self):
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self.link.addNode(-1)
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self.link.addNode(20)
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self.link.addNode(40)
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self.link.printList()
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self.link.removeDuplicatesNoBuffer()
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self.link.printList()
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def test4(self):
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self.link.insertHead(-2)
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self.link.printList()
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if __name__ == "__main__":
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unittest.main()

‎Python/chapter02/2.2 - Return Kth to Last/Nick.py

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#!/usr/bin/python3
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'''
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Return Kth to Last: Implement an algorithm to
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find the kth to last element of a singly linked list.
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'''
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import unittest
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class Node:
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def __init__(self, data, next=None):
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self.data = data
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self.next = next
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def __str__(self):
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return str(self.data)
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class SinglyLinkedList:
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def __init__(self):
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self.head = None
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self.size = 0
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def insertHead(self, data):
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print('Inserting head!----->', data)
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n = Node(data)
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temp = self.head
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self.head = n
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self.head.next = temp
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def addNode(self, data):
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if not self.head:
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n = Node(data)
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print('New Head added ---->', data)
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self.head = n
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else:
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n = self.head
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while (n.next):
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n = n.next
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print('New Node added ---->', data)
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new_node = Node(data)
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n.next = new_node
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def kthToLastElement(self, num):
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if num < 1:
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print('Must be a positive number')
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return
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length = 0
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temp = self.head
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while temp:
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length += 1
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temp = temp.next
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if num > length:
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print('Input number cannot be larger than number of nodes')
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else:
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temp = self.head
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for x in range(length - num):
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temp = temp.next
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print("{}th to last element --->".format(num), temp.data)
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def printList(self):
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n = self.head
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print('Printing Singly Linked List')
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while(n):
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print(n)
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n = n.next
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class Test(unittest.TestCase):
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@classmethod
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def setUpClass(cls):
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cls.link = SinglyLinkedList()
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cls.link.addNode(-1)
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cls.link.addNode(-1)
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cls.link.addNode(4)
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cls.link.addNode(3)
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cls.link.addNode(4)
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cls.link.addNode(1)
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cls.link.addNode(20)
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cls.link.addNode(4)
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cls.link.addNode(4)
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@classmethod
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def tearDownClass(cls):
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print('---Teardown successful---')
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def test1(self):
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self.link.printList()
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def test2(self):
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self.link.kthToLastElement(0)
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self.link.kthToLastElement(1)
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self.link.kthToLastElement(2)
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self.link.kthToLastElement(3)
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self.link.kthToLastElement(9)
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self.link.kthToLastElement(10)
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if __name__ == "__main__":
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unittest.main()

‎Python/chapter02/2.3 - Delete Middle Node/Nick.py

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#!/usr/bin/python3
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import unittest
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from random import randint
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'''
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Delete Middle Node: Implement an algorithm to delete a node in the middle (i.e., any node but the first and last node, not necessarily the exact middle) of a singly linked list, given only access to that node. EXAMPLE lnput:the node c from the linked lista->b->c->d->e->f Result: nothing is returned, but the new linked list looks like a->b->d->e->f Hints:#72
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'''
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'''
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Get clarification on this question:
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1. Will I always know that I will get a middle node? (non end or head node)
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2. What if the node is only 2 lengths long?
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3. What input will I get?
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'''
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class Node:
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def __init__(self, data, next=None):
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self.data = data
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self.next = next
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def __str__(self):
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return str(self.data)
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class SinglyLinkedList:
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def __init__(self):
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self.head = None
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def addNode(self, data):
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# adds node to head if no head
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node = Node(data)
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if not self.head:
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self.head = node
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# adds to end of linked list
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else:
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temp = self.head
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while temp.next:
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temp = temp.next
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temp.next = node
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def printList(self):
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if self.head is None:
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print('Nothing to print')
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return
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temp = self.head
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while temp:
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print(temp.data)
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temp = temp.next
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def findSize(self):
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if self.head is None:
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print('Nothing to find the size of')
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return
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temp = self.head
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count = 0
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while temp:
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count += 1
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temp = temp.next
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return count
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def findMiddleNode(self):
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size = self.findSize()
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if size and size > 2:
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# cannot be the size of the node (tail) or the first node (head)
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temp = self.head
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randomNum = randint(2, size - 1)
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for x in range(1, randomNum):
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temp = temp.next
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return temp
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else:
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print("Not able to access a non head or tail node")
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return None
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def deleteMiddleNode(self, node):
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'''The solution is simply to copy the data
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from the next node over to the current node,
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and then to delete the next node.
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'''
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if node is None:
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print('No node to delete')
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return
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temp = node.next
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node.data = temp.data
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node.next = temp.next
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del temp
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class Test(unittest.TestCase):
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@classmethod
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def setUpClass(cls):
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cls.l = SinglyLinkedList()
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cls.l.addNode(-1)
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cls.l.addNode(3)
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cls.l.addNode('hello')
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cls.l.addNode(100)
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cls.l.addNode(5)
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cls.l.printList()
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@classmethod
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def tearDownClass(self):
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pass
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def test1(self):
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numNodes = self.l.findSize()
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print('Number of nodes {}'.format(numNodes))
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def test2(self):
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node = self.l.findMiddleNode()
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print('Middle node -->', node.data)
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print('Deleting middle node')
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self.l.deleteMiddleNode(node)
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self.l.printList()
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if __name__ == '__main__':
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unittest.main()

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