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1 | 1 | { |
2 | | - "cells": [], |
3 | | - "metadata": {}, |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "code", |
| 5 | + "execution_count": 26, |
| 6 | + "metadata": { |
| 7 | + "collapsed": true |
| 8 | + }, |
| 9 | + "outputs": [], |
| 10 | + "source": [ |
| 11 | + "from math import floor\n", |
| 12 | + "from heapq import merge" |
| 13 | + ] |
| 14 | + }, |
| 15 | + { |
| 16 | + "cell_type": "code", |
| 17 | + "execution_count": 68, |
| 18 | + "metadata": { |
| 19 | + "collapsed": true |
| 20 | + }, |
| 21 | + "outputs": [], |
| 22 | + "source": [ |
| 23 | + "\"\"\"\n", |
| 24 | + "Merge Sort function.\n", |
| 25 | + "1. Uses list operations and merging from heapq to reduce code.\n", |
| 26 | + "2. list[start: end + 1] returns part of the list from start to end.\n", |
| 27 | + "3. Update a section of list directly by doing list[start: end + 1] = update_list\n", |
| 28 | + " (same size)\n", |
| 29 | + "\"\"\"\n", |
| 30 | + "def mergesort(a, start, end):\n", |
| 31 | + " if (start < end):\n", |
| 32 | + " mergesort(a, start, floor((start+end)/2))\n", |
| 33 | + " mergesort(a, floor((start+end)/2) + 1, end)\n", |
| 34 | + " merge_list(a, start, end)\n", |
| 35 | + "\n", |
| 36 | + "# Merge the lists here.\n", |
| 37 | + "def merge_list(a, start, end):\n", |
| 38 | + " mid = floor((start+end)/2) + 1\n", |
| 39 | + " lst = list(merge(a[start: mid], a[mid: end + 1]))\n", |
| 40 | + " a[start: end + 1] = lst\n" |
| 41 | + ] |
| 42 | + }, |
| 43 | + { |
| 44 | + "cell_type": "code", |
| 45 | + "execution_count": 71, |
| 46 | + "metadata": { |
| 47 | + "collapsed": false |
| 48 | + }, |
| 49 | + "outputs": [ |
| 50 | + { |
| 51 | + "name": "stdout", |
| 52 | + "output_type": "stream", |
| 53 | + "text": [ |
| 54 | + "[1, 2, 3, 4, 5, 6, 8, 9, 10]\n" |
| 55 | + ] |
| 56 | + } |
| 57 | + ], |
| 58 | + "source": [ |
| 59 | + "# Testing Sorting functions.\n", |
| 60 | + "a = [2, 1, 4, 6, 5, 3, 10, 9, 8]\n", |
| 61 | + "mergesort(a, 0, len(a) - 1)\n", |
| 62 | + "print(a)" |
| 63 | + ] |
| 64 | + } |
| 65 | + ], |
| 66 | + "metadata": { |
| 67 | + "kernelspec": { |
| 68 | + "display_name": "Python 3", |
| 69 | + "language": "python", |
| 70 | + "name": "python3" |
| 71 | + }, |
| 72 | + "language_info": { |
| 73 | + "codemirror_mode": { |
| 74 | + "name": "ipython", |
| 75 | + "version": 3 |
| 76 | + }, |
| 77 | + "file_extension": ".py", |
| 78 | + "mimetype": "text/x-python", |
| 79 | + "name": "python", |
| 80 | + "nbconvert_exporter": "python", |
| 81 | + "pygments_lexer": "ipython3", |
| 82 | + "version": "3.4.3" |
| 83 | + } |
| 84 | + }, |
4 | 85 | "nbformat": 4, |
5 | 86 | "nbformat_minor": 0 |
6 | 87 | } |
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