euler-008-largest-product-in-a-series-20160324.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "from __future__ import print_function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import string\n",
    "import operator\n",
    "from functools import reduce"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(1000,\n",
       " 7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450)"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "s = '''\n",
    " 73167176531330624919225119674426574742355349194934\n",
    " 96983520312774506326239578318016984801869478851843\n",
    " 85861560789112949495459501737958331952853208805511\n",
    " 12540698747158523863050715693290963295227443043557\n",
    " 66896648950445244523161731856403098711121722383113\n",
    " 62229893423380308135336276614282806444486645238749\n",
    " 30358907296290491560440772390713810515859307960866\n",
    " 70172427121883998797908792274921901699720888093776\n",
    " 65727333001053367881220235421809751254540594752243\n",
    " 52584907711670556013604839586446706324415722155397\n",
    " 53697817977846174064955149290862569321978468622482\n",
    " 83972241375657056057490261407972968652414535100474\n",
    " 82166370484403199890008895243450658541227588666881\n",
    " 16427171479924442928230863465674813919123162824586\n",
    " 17866458359124566529476545682848912883142607690042\n",
    " 24219022671055626321111109370544217506941658960408\n",
    " 07198403850962455444362981230987879927244284909188\n",
    " 84580156166097919133875499200524063689912560717606\n",
    " 05886116467109405077541002256983155200055935729725\n",
    " 71636269561882670428252483600823257530420752963450\n",
    " '''\n",
    "s=int(''.join(c for c in s if c in string.digits))\n",
    "len(str(s)), s"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "def foo(s, n):\n",
    "    s = str(s)\n",
    "    biggest_product = 0\n",
    "    for i in range(len(s) - n + 1):\n",
    "        t = s[i:i+n]\n",
    "        product = reduce(operator.mul, map(int, t))\n",
    "        if product > biggest_product:\n",
    "            biggest_product = product\n",
    "    return biggest_product"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "5832"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "foo(s, 4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "100 loops, best of 3: 3.72 ms per loop\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "23514624000"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "n = 13\n",
    "%timeit foo(s, n)\n",
    "foo(s, n)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "def foo(s, n):\n",
    "    s = str(s)\n",
    "    adjacent_digits = (s[i:i+n] for i in range(len(s) - n + 1))\n",
    "    products = (\n",
    "        reduce(operator.mul, map(int, t))\n",
    "        for t in adjacent_digits)\n",
    "    return max(products)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "100 loops, best of 3: 3.88 ms per loop\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "23514624000"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "n = 13\n",
    "%timeit foo(s, n)\n",
    "foo(s, n)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "def foo(s, n):\n",
    "    s = str(s)\n",
    "    return max(\n",
    "        reduce(operator.mul, map(int, s[i:i+n]))\n",
    "        for i in range(len(s) - n + 1))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "100 loops, best of 3: 3.82 ms per loop\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "23514624000"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "n = 13\n",
    "%timeit foo(s, n)\n",
    "foo(s, n)"
   ]
  }
 ],
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