88 lines
1.7 KiB
Plaintext
88 lines
1.7 KiB
Plaintext
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Euler Problem 20\n",
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"\n",
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"n! means n × (n − 1) × ... × 3 × 2 × 1\n",
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"\n",
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"For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,\n",
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"and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.\n",
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"\n",
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"Find the sum of the digits in the number 100!"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Write our own factorial implementation and get the solution."
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"def factorial(n):\n",
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" assert(n > 0)\n",
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" if n == 1:\n",
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" return 1\n",
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" else:\n",
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" return n * factorial(n - 1)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 2,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"648\n"
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]
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}
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],
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"source": [
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"f100 = factorial(100)\n",
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"print(sum(map(int, str(f100))))\n",
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"assert(sum(map(int, str(f100))) == 648)"
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]
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}
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],
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"metadata": {
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"completion_date": "Fri, 5 Sep 2014, 10:42",
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"kernelspec": {
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"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.5.4"
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},
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"tags": [
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"factorial"
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]
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},
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"nbformat": 4,
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"nbformat_minor": 0
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}
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