joeyajames/udemy_data_structures
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

initial upload of all course files

Browse Source
This commit is contained in:
Joe James
2019-05-01 22:08:49 -07:00
committed by GitHub
parent d91f88d3a9
commit 7f2424ce24
15 changed files with 2872 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

439
Section_3/Python Linked Lists.ipynb Normal file
View File

@@ -0,0 +1,439 @@
{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Python Linked Lists"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Node Class\n",
"Node class has a constructor that sets the data passed in, and optionally can set the next_node and prev_node. \n",
"It also has a str method to give a string representation for printing. \n",
"Note that prev_node is only used for Doubly Linked Lists."
]
},
{
"cell_type": "code",
"execution_count": 128,
"metadata": {},
"outputs": [],
"source": [
"class Node:\n",
"\n",
" def __init__ (self, d, n=None, p=None):\n",
" self.data = d\n",
" self.next_node = n\n",
" self.prev_node = p\n",
" \n",
" def __str__ (self):\n",
" return ('(' + str(self.data) + ')')"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### LinkedList Class\n",
"A LinkedList object has two attributes: a root node that defaults to None, and size that defaults to 0.\n",
" \n",
"**Add** method receives a piece of data, creates a new Node, setting the root as its next_node, changes the LL's root pointer to the new node, and increments size.\n",
"\n",
"**Find** iterates through the nodes until it finds the data passed in. If if finds the data it will return it, otherwise returns None.\n",
"\n",
"**Remove** needs pointers to this_node and prev_node. If it finds the data, it needs to check if it is in the root node (prev_node is None) before deciding how to bypass the deleted node.\n",
"\n",
"**Print_list** iterates the list and prints each node."
]
},
{
"cell_type": "code",
"execution_count": 129,
"metadata": {},
"outputs": [],
"source": [
"class LinkedList:\n",
"\n",
" def __init__(self, r = None):\n",
" self.root = r\n",
" self.size = 0\n",
"\n",
" def add(self, d):\n",
" new_node = Node(d, self.root)\n",
" self.root = new_node\n",
" self.size += 1\n",
" \n",
" def find(self, d):\n",
" this_node = self.root\n",
" while this_node is not None:\n",
" if this_node.data == d:\n",
" return d\n",
" else:\n",
" this_node = this_node.next_node\n",
" return None\n",
"\n",
" def remove(self, d):\n",
" this_node = self.root\n",
" prev_node = None\n",
"\n",
" while this_node is not None:\n",
" if this_node.data == d:\n",
" if prev_node is not None: # data is in non-root\n",
" prev_node.next_node = this_node.next_node\n",
" else: # data is in root node\n",
" self.root = this_node.next_node\n",
" self.size -= 1\n",
" return True # data removed\n",
" else:\n",
" prev_node = this_node\n",
" this_node = this_node.next_node\n",
" return False # data not found\n",
" \n",
" def print_list(self):\n",
" this_node = self.root\n",
" while this_node is not None:\n",
" print(this_node, end='->')\n",
" this_node = this_node.next_node\n",
" print('None')"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Linked List Test Code\n",
"This test code adds nodes to the LinkedList, Prints the list, prints the size, removes an item, and finds an item."
]
},
{
"cell_type": "code",
"execution_count": 130,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"(12)->(8)->(5)->None\n",
"size=3\n",
"size=2\n",
"5\n",
"(12)\n"
]
}
],
"source": [
"myList = LinkedList()\n",
"myList.add(5)\n",
"myList.add(8)\n",
"myList.add(12)\n",
"myList.print_list()\n",
"\n",
"print(\"size=\"+str(myList.size))\n",
"myList.remove(8)\n",
"print(\"size=\"+str(myList.size))\n",
"print(myList.find(5))\n",
"print(myList.root)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"-----\n",
"### Circular Linked List\n",
"Includes attributes root and size. \n",
"Includes methods add, find, remove, and print_list."
]
},
{
"cell_type": "code",
"execution_count": 131,
"metadata": {},
"outputs": [],
"source": [
"class CircularLinkedList:\n",
"\n",
" def __init__ (self, r = None):\n",
" self.root = r\n",
" self.size = 0\n",
"\n",
" def add (self, d):\n",
" if self.size == 0:\n",
" self.root = Node(d)\n",
" self.root.next_node = self.root\n",
" else:\n",
" new_node = Node (d, self.root.next_node)\n",
" self.root.next_node = new_node\n",
" self.size += 1\n",
"\n",
" def find (self, d):\n",
" this_node = self.root\n",
" while True:\n",
" if this_node.data == d:\n",
" return d\n",
" elif this_node.next_node == self.root:\n",
" return False\n",
" this_node = this_node.next_node\n",
"\n",
" def remove (self, d):\n",
" this_node = self.root\n",
" prev_node = None\n",
"\n",
" while True:\n",
" if this_node.data == d: # found\n",
" if prev_node is not None:\n",
" prev_node.next_node = this_node.next_node\n",
" else:\n",
" while this_node.next_node != self.root:\n",
" this_node = this_node.next_node\n",
" this_node.next_node = self.root.next_node\n",
" self.root = self.root.next_node\n",
" self.size -= 1\n",
" return True # data removed\n",
" elif this_node.next_node == self.root:\n",
" return False # data not found\n",
" prev_node = this_node\n",
" this_node = this_node.next_node\n",
" \n",
" def print_list (self):\n",
" if self.root is None:\n",
" return\n",
" this_node = self.root\n",
" print (this_node, end='->')\n",
" while this_node.next_node != self.root:\n",
" this_node = this_node.next_node\n",
" print (this_node, end='->')\n",
" print()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Circular Linked List Test Code"
]
},
{
"cell_type": "code",
"execution_count": 132,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"size=5\n",
"8\n",
"False\n",
"(5)->(9)->(8)->(3)->(7)->(5)->(9)->(8)->(3)->\n"
]
}
],
"source": [
"cll = CircularLinkedList()\n",
"for i in [5, 7, 3, 8, 9]:\n",
" cll.add(i)\n",
"\n",
"print(\"size=\"+str(cll.size))\n",
"print(cll.find(8))\n",
"print(cll.find(12))\n",
"\n",
"my_node = cll.root\n",
"print (my_node, end='->')\n",
"for i in range(8):\n",
" my_node = my_node.next_node\n",
" print (my_node, end='->')\n",
"print()"
]
},
{
"cell_type": "code",
"execution_count": 133,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"(5)->(9)->(8)->(3)->(7)->\n",
"False\n",
"size=4\n",
"(9)->(3)->(7)->\n"
]
}
],
"source": [
"cll.print_list()\n",
"cll.remove(8)\n",
"print(cll.remove(15))\n",
"print(\"size=\"+str(cll.size))\n",
"cll.remove(5) # delete root node\n",
"cll.print_list()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"-----\n",
"### Doubly Linked List"
]
},
{
"cell_type": "code",
"execution_count": 134,
"metadata": {},
"outputs": [],
"source": [
"class DoublyLinkedList:\n",
"\n",
" def __init__ (self, r = None):\n",
" self.root = r\n",
" self.last = r\n",
" self.size = 0\n",
"\n",
" def add (self, d):\n",
" if self.size == 0:\n",
" self.root = Node(d)\n",
" self.last = self.root\n",
" else:\n",
" new_node = Node(d, self.root)\n",
" self.root.prev_node = new_node\n",
" self.root = new_node\n",
" self.size += 1\n",
"\n",
" def find (self, d):\n",
" this_node = self.root\n",
" while this_node is not None:\n",
" if this_node.data == d:\n",
" return d\n",
" elif this_node.next_node == None:\n",
" return False\n",
" else:\n",
" this_node = this_node.next_node\n",
"\n",
" def remove (self, d):\n",
" this_node = self.root\n",
" while this_node is not None:\n",
" if this_node.data == d:\n",
" if this_node.prev_node is not None:\n",
" if this_node.next_node is not None: # delete a middle node\n",
" this_node.prev_node.next_node = this_node.next_node\n",
" this_node.next_node.prev_node = this_node.prev_node\n",
" else: # delete last node\n",
" this_node.prev_node.next_node = None\n",
" self.last = this_node.prev_node\n",
" else: # delete root node\n",
" self.root = this_node.next_node\n",
" this_node.next_node.prev_node = self.root\n",
" self.size -= 1\n",
" return True # data removed\n",
" else:\n",
" this_node = this_node.next_node\n",
" return False # data not found\n",
" \n",
" def print_list (self):\n",
" if self.root is None:\n",
" return\n",
" this_node = self.root\n",
" print (this_node, end='->')\n",
" while this_node.next_node is not None:\n",
" this_node = this_node.next_node\n",
" print (this_node, end='->')\n",
" print()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Doubly Linked List Test Code"
]
},
{
"cell_type": "code",
"execution_count": 135,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"size=5\n",
"(9)->(8)->(3)->(9)->(5)->\n",
"size=4\n"
]
}
],
"source": [
"dll = DoublyLinkedList()\n",
"for i in [5, 9, 3, 8, 9]:\n",
" dll.add(i)\n",
"\n",
"print(\"size=\"+str(dll.size))\n",
"dll.print_list()\n",
"dll.remove(8)\n",
"print(\"size=\"+str(dll.size))"
]
},
{
"cell_type": "code",
"execution_count": 136,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"False\n",
"False\n",
"(22)->(21)->(9)->(3)->(9)->\n",
"(3)\n"
]
}
],
"source": [
"print(dll.remove(15))\n",
"print(dll.find(15))\n",
"dll.add(21)\n",
"dll.add(22)\n",
"dll.remove(5)\n",
"dll.print_list()\n",
"print(dll.last.prev_node)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.7.0"
}
},
"nbformat": 4,
"nbformat_minor": 2
}

BIN
Section_3/Python Linked Lists.pdf Normal file
View File

Binary file not shown.