diff --git a/README.md b/README.md index f6053b0..4fff186 100644 --- a/README.md +++ b/README.md @@ -46,6 +46,7 @@ Most solutions are in Python. ## Sorting and Searching * [Implement selection sort](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/sorting-searching/selection-sort.ipynb#) +* [Implement insertion sort](http://nbviewer.ipython.org/github/donnemartin/algorithms-data-structures/blob/master/sorting-searching/insertion-sort.ipynb#) ## Hacker Rank diff --git a/sorting-searching/insertion-sort.ipynb b/sorting-searching/insertion-sort.ipynb new file mode 100644 index 0000000..333915d --- /dev/null +++ b/sorting-searching/insertion-sort.ipynb @@ -0,0 +1,124 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Problem: Implement insertion sort.\n", + "\n", + "* [Clarifying Questions](#Clarifying-Questions)\n", + "* [Test Cases](#Test-Cases)\n", + "* [Algorithm](#Algorithm)\n", + "* [Code](#Code)\n", + "* [Pythonic-Code](#Pythonic-Code)" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Clarifying Questions\n", + "\n", + "* Are we sorting integers?\n", + " * Yes\n", + "* Can we assume the input is valid integers?\n", + " * Yes\n", + "* Can we have duplicate integers?\n", + " * Yes" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Test Cases\n", + "\n", + "* Empty input\n", + "* One element\n", + "* Two or more elements" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Algorithm\n", + "\n", + "Wikipedia's animation:\n", + "![alt text](http://upload.wikimedia.org/wikipedia/commons/0/0f/Insertion-sort-example-300px.gif)\n", + "\n", + "* For each value index 1 to n - 1\n", + " * Compare with all elements to the left of the current value to determine new insertion point\n", + " * Hold current value in temp variable\n", + " * Shift elements from new insertion point right\n", + " * Insert value in temp variable\n", + " * Break\n", + "\n", + "Complexity:\n", + "* Time: O(n^2) avarage, worst. O(1) best if input is already sorted.\n", + "* Space: O(1)" + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## Code" + ] + }, + { + "cell_type": "code", + "execution_count": null, + "metadata": { + "collapsed": false + }, + "outputs": [], + "source": [ + "def insertion_sort(data):\n", + " if len(data) < 2:\n", + " return\n", + " for r in xrange(1, len(data)):\n", + " for l in xrange(0, r):\n", + " if data[l] > data[r]:\n", + " temp = data[r]\n", + " data[l+1:r+1] = data[l:r]\n", + " data[l] = temp\n", + " break\n", + "\n", + "print('Empty input')\n", + "data = []\n", + "insertion_sort(data)\n", + "print(data)\n", + "print('One element')\n", + "data = [5]\n", + "insertion_sort(data)\n", + "print(data)\n", + "print('Two or more elements')\n", + "data = [5, 1, 7, 2, 6, -3, 5, 7, -1]\n", + "insertion_sort(data)\n", + "print(data)" + ] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 2", + "language": "python", + "name": "python2" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 2 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython2", + "version": "2.7.9" + } + }, + "nbformat": 4, + "nbformat_minor": 0 +}