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Added notebook solving the following: Partition a linked list around a given value.
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Donne Martin
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@ -18,6 +18,7 @@ Continually updated IPython Notebooks containing algorithms and data structures.
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* [Remove duplicates from a linked list](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/remove-duplicates.ipynb)
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* [Remove duplicates from a linked list](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/remove-duplicates.ipynb)
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* [Find the kth to last element of a linked list](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/kth-to-last-elem.ipynb)
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* [Find the kth to last element of a linked list](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/kth-to-last-elem.ipynb)
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* [Delete a node in the middle of a linked list, given access to only that node](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/delete-mid.ipynb)
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* [Delete a node in the middle of a linked list, given access to only that node](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/delete-mid.ipynb)
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* [Partition a linked list around a given value](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/linked-lists/partition.ipynb)
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## License
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## License
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178
linked-lists/partition.ipynb
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178
linked-lists/partition.ipynb
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@ -0,0 +1,178 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Partition a linked list around a value x, such that all nodes less than x come before all nodes greater than or equal to x.\n",
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"\n",
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"* [Clarifying Questions](#Clarifying-Questions)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Pythonic-Code](#Pythonic-Code)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Clarifying Questions\n",
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"\n",
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"* Can we create additional data structures?\n",
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" * Yes\n",
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"* Do you expect the function to return a new list?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* Empty list\n",
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"* One element list\n",
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"* Left linked list is empty\n",
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"* Right linked list is empty\n",
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"* X invalid\n",
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"* General case\n",
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" * Partition = 10\n",
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" * Input: 4, 3, 7, 8, 10, 1, 10, 12\n",
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" * Output: 4, 3, 7, 8, 1, 10, 10, 12"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"* Test error cases\n",
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"* Create left and right linked lists\n",
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"* For each element in the list\n",
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" * If elem < x, append to the left list\n",
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" * else, append to the right list\n",
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"* Merge left and right lists\n",
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"\n",
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"Complexity:\n",
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"* Time: O(n)\n",
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"* Space: O(n)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run linked_list.py"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"class MyLinkedList(LinkedList):\n",
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" def partition(self, data):\n",
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" if self.head is None:\n",
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" return\n",
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" if type(data) != int:\n",
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" raise ValueError('Invalid int argument: data')\n",
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" left = MyLinkedList(None)\n",
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" right = MyLinkedList(None)\n",
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" curr = self.head\n",
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" while curr is not None:\n",
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" if curr.data < data:\n",
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" left.append(curr.data)\n",
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" else:\n",
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" right.append(curr.data)\n",
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" curr = curr.next\n",
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" curr_left = left.head\n",
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" if curr_left is None:\n",
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" return right\n",
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" else:\n",
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" while curr_left.next is not None:\n",
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" curr_left = curr_left.next\n",
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" curr_left.next = right.head\n",
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" return left"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"print('Empty list')\n",
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"linked_list = MyLinkedList(None)\n",
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"linked_list.partition(10)\n",
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"linked_list.print_list()\n",
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"print('X invalid')\n",
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"head = Node(12)\n",
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"linked_list = MyLinkedList(head)\n",
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"try:\n",
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" linked_list.partition('a')\n",
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"except ValueError as err:\n",
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" print(err)\n",
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"linked_list.print_list()\n",
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"print('One element list')\n",
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"print('Left linked list is empty')\n",
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"linked_list.partition(1)\n",
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"linked_list.print_list()\n",
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"print('Right linked list is empty')\n",
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"linked_list.partition(20)\n",
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"linked_list.print_list()\n",
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"print('General case')\n",
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"# Partition = 10\n",
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"# Input 4, 3, 7, 8, 10, 1, 10, 12\n",
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"# Output 4, 3, 7, 8, 1, 10, 10, 12\n",
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"linked_list.insert_to_front(10)\n",
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"linked_list.insert_to_front(1)\n",
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"linked_list.insert_to_front(10)\n",
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"linked_list.insert_to_front(8)\n",
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"linked_list.insert_to_front(7)\n",
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"linked_list.insert_to_front(3)\n",
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"linked_list.insert_to_front(4)\n",
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"partitioned_list = linked_list.partition(10)\n",
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"partitioned_list.print_list()"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 2",
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"language": "python",
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"name": "python2"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 2
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython2",
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"version": "2.7.9"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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