{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "## algorithm" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": true }, "outputs": [], "source": [ "def search(text, pattern):\n", " i, k = 0, len(pattern)\n", " table = {c: k - i for i, c in enumerate(pattern)}\n", "\n", " while True:\n", " print(f'search @ {i}')\n", " if text[i:i + k] == pattern:\n", " print(f'FOUND @ {i}')\n", " if i + k < len(text):\n", " i += table.get(text[i + k], k + 1)\n", " else:\n", " break" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## run" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "collapsed": false }, "outputs": [ { "data": { "text/plain": [ "73" ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "text = 'A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror)'\n", "len(text)" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "search @ 0\n", "search @ 10\n", "search @ 20\n", "search @ 30\n", "search @ 40\n", "search @ 44\n", "FOUND @ 44\n", "search @ 54\n", "search @ 56\n", "search @ 66\n" ] } ], "source": [ "search(text, 'reflector')" ] }, { "cell_type": "code", "execution_count": 4, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "search @ 0\n", "search @ 6\n", "search @ 10\n", "search @ 11\n", "search @ 17\n", "search @ 33\n", "search @ 40\n", "search @ 44\n", "search @ 60\n" ] } ], "source": [ "search(text, 'not to be found')" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "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": "3.6.0" } }, "nbformat": 4, "nbformat_minor": 2 }