mirror of
https://github.com/donnemartin/interactive-coding-challenges
synced 2026-01-07 18:08:01 +00:00
Added stack challenge.
This commit is contained in:
Donne Martin
218
stacks_queues/stack/stack_challenge.ipynb
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218
stacks_queues/stack/stack_challenge.ipynb
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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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"<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
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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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"# Challenge Notebook"
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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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"## Problem: Implement a stack with push, pop, peek, and is_empty methods using a linked list.\n",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)\n",
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"* [Pythonic-Code](#Pythonic-Code)\n",
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"* [Solution Notebook](#Solution-Notebook)"
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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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"## Constraints\n",
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"\n",
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"*Problem statements are sometimes ambiguous. Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
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"\n",
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"* None"
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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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"## Test Cases\n",
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"\n",
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"### Push\n",
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"\n",
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"* Push to empty stack\n",
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"* Push to non-empty stack\n",
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"\n",
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"### Pop\n",
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"\n",
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"* Pop on empty stack\n",
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"* Pop on single element stack\n",
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"* Pop on multiple element stack\n",
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"\n",
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"### Peek\n",
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"\n",
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"* Peek on empty stack\n",
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"* Peek on one or more element stack\n",
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"\n",
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"### Is Empty\n",
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"\n",
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"* Is empty on empty stack\n",
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"* Is empty on one or more element stack"
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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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"## Algorithm\n",
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"\n",
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"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/stack/stack_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
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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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"## Code"
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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": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"class Node(object):\n",
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" \n",
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" def __init__(self, data):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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"class Stack(object):\n",
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" \n",
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" def __init__(self, top=None):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def push(self, data):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def pop(self):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def peek(self):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def is_empty(self):\n",
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" # TODO: Implement me\n",
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" pass"
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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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"## Unit Test\n",
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"\n",
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"\n",
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"\n",
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"**The following unit test is expected to fail until you solve the challenge.**"
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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": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"# %load test_stack.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"\n",
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"class TestStack(object):\n",
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" \n",
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" # TODO: It would be better if we had unit tests for each\n",
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" # method in addition to the following end-to-end test\n",
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" def test_end_to_end(self):\n",
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" print('Test: Empty stack')\n",
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" stack = Stack()\n",
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" assert_equal(stack.peek(), None)\n",
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" assert_equal(stack.pop(), None)\n",
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"\n",
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" print('Test: One element')\n",
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" top = Node(5)\n",
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" stack = Stack(top)\n",
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" assert_equal(stack.pop(), 5)\n",
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" assert_equal(stack.peek(), None)\n",
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"\n",
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" print('Test: More than one element')\n",
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" stack = Stack()\n",
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" stack.push(1)\n",
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" stack.push(2)\n",
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" stack.push(3)\n",
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" assert_equal(stack.pop(), 3)\n",
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" assert_equal(stack.peek(), 2)\n",
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" assert_equal(stack.pop(), 2)\n",
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" assert_equal(stack.peek(), 1)\n",
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" assert_equal(stack.is_empty(), False)\n",
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" assert_equal(stack.pop(), 1)\n",
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" assert_equal(stack.peek(), None)\n",
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" assert_equal(stack.is_empty(), True)\n",
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" \n",
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" print('Success: test_end_to_end')\n",
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"\n",
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"def main():\n",
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" test = TestStack()\n",
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" test.test_end_to_end()\n",
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" \n",
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"if __name__ == '__main__':\n",
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" main()"
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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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"## Solution Notebook\n",
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"\n",
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"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/stack/stack_solution.ipynb) for a discussion on algorithms and code solutions."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 2",
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"language": "python",
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"name": "python2"
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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": 2
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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": "ipython2",
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"version": "2.7.10"
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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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