mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
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adds "remove specified char in given string" challenge and its solution
This commit is contained in:
muatik
parent
6276624914
commit
df107d6278
0
arrays_strings/remove_char/__init__.py
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0
arrays_strings/remove_char/__init__.py
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159
arrays_strings/remove_char/remove_char_challenge.ipynb
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arrays_strings/remove_char/remove_char_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 [Mustafa Atik](https://www.linkedin.com/in/muatik). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-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 funciton which removes specified character in a given string.\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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"* [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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"* Can I assume the string is ASCII?\n",
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" * Yes\n",
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" * Note: Unicode strings could require special handling depending on your language"
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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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"* \"a\" from \"tamamdir arAda\" -> \"tmmdir rAd\""
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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/interactive-coding-challenges/blob/master/arrays_strings/hash_map/hash_map_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": true
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},
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"outputs": [],
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"source": [
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"def remove_char(string, char):\n",
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" # TODO: Implement me\n",
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" pass\n"
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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"
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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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"\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_hash_map.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 TestRemoveChar(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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" assert_equal(remove_char(\"tamamdir arAda\", \"a\"), \"tmmdir rAd\")\n",
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" assert_equal(remove_char(\"wlkwlkfew wifiw longgglonggggw\", \"w\"), \"lklkfe ifi longgglongggg\")\n",
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" assert_equal(remove_char(\"yu*lkke*\", \"*\"), \"yulkke\")\n",
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" print('Success: remove_car')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestHashMap()\n",
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" test.test_end_to_end()\n",
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"\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/interactive-coding-challenges/blob/master/arrays_strings/hash_map/hash_map_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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185
arrays_strings/remove_char/remove_char_solution.ipynb
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185
arrays_strings/remove_char/remove_char_solution.ipynb
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@ -0,0 +1,185 @@
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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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"### Constraints\n",
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"\n",
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"* Can I assume the string is ASCII?\n",
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" * Yes\n",
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" * Note: Unicode strings could require special handling depending on your language\n",
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"\n",
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"Test Case\n",
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"\n",
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"* \"a\" from \"tamamdir arAda\" -> \"tmmdir rAd\"\n"
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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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"Since Python strings are immutable, we'll use a list of chars instead to exercise in-place string manipulation as you would get with a C string.\n",
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"\n",
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"create a list as a string builder\n",
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"\n",
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"* for each character in string\n",
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"* * checks whether the current char is not equal to removalChar\n",
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"* * keep the char in the list\n",
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" \n",
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"#### Complexity:\n",
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"\n",
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"* Time: O(n)\n",
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"* Space: O(n)"
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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": 45,
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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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"def remove_char(string, char):\n",
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" newString = []\n",
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" for i in string:\n",
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" if char != i:\n",
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" newString.append(i)\n",
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" return \"\".join(newString)"
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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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"### Pythonic way\n",
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"\n",
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"You can achive the same goal in a concise way by using python's string modidication methods as follows:"
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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": 46,
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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 remove_char2(string, char):\n",
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" return string.translate(None, char)\n",
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"\n",
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"def remove_char3(string, char):\n",
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" return string.replace(char, \"\")\n"
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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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"### Unittests"
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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": 47,
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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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"Success\n",
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"Success\n",
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"Success\n"
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]
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}
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],
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"source": [
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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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"def testWith(func):\n",
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" assert_equal(func(\"tamamdir arAda\", \"a\"), \"tmmdir rAd\")\n",
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" assert_equal(func(\"wlkwlkfew wifiw longgglonggggw\", \"w\"), \"lklkfe ifi longgglongggg\")\n",
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" assert_equal(func(\"yu*lkke*\", \"*\"), \"yulkke\")\n",
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" \n",
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" print('Success')\n",
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"testWith(remove_char)\n",
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"testWith(remove_char2)\n",
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"testWith(remove_char3)\n"
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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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"### Benchmark"
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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": 49,
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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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"remove_char 5.82854199409\n",
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"remove_char2 0.402535915375\n",
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"remove_char3 0.377779960632\n"
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]
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}
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],
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"source": [
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"import timeit\n",
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"print \"remove_char\", timeit.timeit(\n",
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" \"remove_char('wlkwlkfew wifiw longgglonggggw', 'a')\",\n",
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" \"from __main__ import remove_char\", number=1200000)\n",
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"print \"remove_char2\", timeit.timeit(\n",
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" \"remove_char2('wlkwlkfew wifiw longgglonggggw', 'a')\",\n",
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" \"from __main__ import remove_char2\", number=1200000)\n",
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"print \"remove_char3\", timeit.timeit(\n",
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" \"remove_char3('wlkwlkfew wifiw longgglonggggw', 'a')\",\n",
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" \"from __main__ import remove_char3\", number=1200000)"
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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": true
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},
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"outputs": [],
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"source": []
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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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