{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "t = 'haystack needle haystack' # \"text\" - thing we search in\n",
    "p = 'needle' # \"pattern\" - thing we search for"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "def naive(p, t):\n",
    "    assert len(p) <= len(t)  # assume text at least as long as pattern\n",
    "    occurrences = []\n",
    "    for i in range(len(t)-len(p)+1):  # for each alignment of p to t\n",
    "        match = True  # assume we match until proven wrong\n",
    "        for j in range(len(p)):  # for each position of p\n",
    "            if t[i+j] != p[j]:\n",
    "                match = False  # at least 1 char mismatches\n",
    "                break\n",
    "        if match:\n",
    "            occurrences.append(i)\n",
    "    return occurrences"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[9]"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "naive(p, t)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'needle'"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "t[9:9+len(p)]  # confirm it really occurs"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[0, 6, 12]"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "naive('needle', 'needleneedleneedle')"
   ]
  }
 ],
 "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": "2.7.14"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 1
}