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https://github.com/donnemartin/interactive-coding-challenges.git
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Add flip bit challenge
This commit is contained in:
Donne Martin
parent
d4d819b476
commit
c06594871d
0
bit_manipulation/flip_bit/__init__.py
Normal file
0
bit_manipulation/flip_bit/__init__.py
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182
bit_manipulation/flip_bit/flip_bit_challenge.ipynb
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182
bit_manipulation/flip_bit/flip_bit_challenge.ipynb
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@ -0,0 +1,182 @@
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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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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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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: Flip one bit from 0 to 1 to maximize the longest sequence of 1s.\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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"* Is the input an int, base 2?\n",
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" * Yes\n",
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"* Can we assume the input is a 32 bit number?\n",
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" * Yes\n",
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"* Do we have to validate the length of the input?\n",
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" * No\n",
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"* Is the output an int?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * No\n",
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"* Can we assume we are using a positive number since Python doesn't have an >>> operator?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\n",
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" * Yes"
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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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"* None -> Exception\n",
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"* All 1's -> Count of 1s\n",
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"* All 0's -> 1\n",
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"* General case\n",
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" * 0000 1111 1101 1101 1111 0011 1111 0000 -> 10 (ten)"
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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](). 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 Bits(object):\n",
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"\n",
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" def flip_bit(self, num):\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"
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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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"**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_flip_bit.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBits(object):\n",
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"\n",
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" def test_flip_bit(self):\n",
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" bits = Bits()\n",
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" assert_raises(TypeError, bits.flip_bit, None)\n",
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" assert_equal(bits.flip_bit(0), 1)\n",
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" assert_equal(bits.flip_bit(-1), bits.MAX_BITS)\n",
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" num = int('00001111110111011110001111110000', base=2)\n",
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" expected = 10\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
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" num = int('00000100111011101111100011111011', base=2)\n",
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" expected = 9\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
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" num = int('00010011101110111110001111101111', base=2)\n",
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" expected = 10\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
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" print('Success: test_print_binary')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBits()\n",
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" test.test_flip_bit()\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]() 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 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": "3.5.0"
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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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275
bit_manipulation/flip_bit/flip_bit_solution.ipynb
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275
bit_manipulation/flip_bit/flip_bit_solution.ipynb
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@ -0,0 +1,275 @@
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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": {},
|
||||
"source": [
|
||||
"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges)."
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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"
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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: Flip one bit from 0 to 1 to maximize the longest sequence of 1s.\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)"
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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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"* Is the input an int, base 2?\n",
|
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" * Yes\n",
|
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"* Can we assume the input is a 32 bit number?\n",
|
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" * Yes\n",
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"* Do we have to validate the length of the input?\n",
|
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" * No\n",
|
||||
"* Is the output an int?\n",
|
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" * Yes\n",
|
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"* Can we assume the inputs are valid?\n",
|
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" * No\n",
|
||||
"* Can we assume we are using a positive number since Python doesn't have an >>> operator?\n",
|
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" * Yes\n",
|
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"* Can we assume this fits memory?\n",
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" * Yes"
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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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"* None -> Exception\n",
|
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"* All 1's -> Count of 1s\n",
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"* All 0's -> 1\n",
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"* General case\n",
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" * Trailing zeroes\n",
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" * 0000 1111 1101 1101 1111 0011 1111 0000 -> 10 (ten)\n",
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" * Trailing ones\n",
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" * 0000 1001 1101 1101 1111 0001 1111 0111 -> 9"
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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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"* seen = []\n",
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"* Build a list of sequence counts\n",
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" * Look for 0's\n",
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" * This will be 0 length if the input has trailing ones\n",
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" * Add sequence length to seen\n",
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" * Look for 1's\n",
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" * Add sequence length to seen\n",
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"* Find the largest sequence of ones looking at seen\n",
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" * Loop through seen\n",
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" * On each iteration of the loop, flip what we are looking for from 0 to 1 and vice versa\n",
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" * If seen[i] represents 1's, continue, we only want to process 0's\n",
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" * If this is our first iteration:\n",
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" * max_result = seen[i+1] + 1 if seen[i] > 0\n",
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" * continue\n",
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" * If we are looking at leading zeroes (i == len(seen)-1):\n",
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" * result = seen[i-1] + 1\n",
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" * If we are looking at one zero:\n",
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" * result = seen[i+1] + seen[i-1] + 1\n",
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" * If we are looking at multiple zeroes:\n",
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" * result = max(seen[i+1], seen[i-1]) + 1\n",
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" * Update max_result based on result\n",
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"\n",
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"We should make a note that Python does not have a logical right shift operator built in. We can either use a positive number or implement one for a 32 bit number:\n",
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"\n",
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" num % 0x100000000 >> n\n",
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" \n",
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"Complexity:\n",
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"* Time: O(b)\n",
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"* Space: O(b)"
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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": 1,
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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 Bits(object):\n",
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"\n",
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" MAX_BITS = 32\n",
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" \n",
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" def _build_seen_list(self, num):\n",
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" seen = []\n",
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" looking_for = 0\n",
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" count = 0\n",
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" for _ in range(self.MAX_BITS):\n",
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" if num & 1 != looking_for:\n",
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" seen.append(count)\n",
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" looking_for = not looking_for\n",
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" count = 0\n",
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" count += 1\n",
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" num >>= 1\n",
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" seen.append(count)\n",
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" return seen\n",
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" \n",
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" def flip_bit(self, num):\n",
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" if num is None:\n",
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" raise TypeError('num cannot be None')\n",
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" if num == -1:\n",
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" return self.MAX_BITS\n",
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" if num == 0:\n",
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" return 1\n",
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" seen = self._build_seen_list(num)\n",
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" max_result = 0\n",
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" looking_for = 0\n",
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" for index, count in enumerate(seen):\n",
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" result = 0\n",
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" # Only look for zeroes\n",
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" if looking_for == 1:\n",
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" looking_for = not looking_for\n",
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" continue\n",
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" # First iteration, take trailing zeroes\n",
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" # or trailing ones into account\n",
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" if index == 0:\n",
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" if count != 0:\n",
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" # Trailing zeroes\n",
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" try:\n",
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" result = seen[index + 1] + 1\n",
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" except IndexError:\n",
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" result = 1\n",
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" # Last iteration\n",
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" elif index == len(seen) - 1:\n",
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" result = 1 + seen[index - 1]\n",
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" else:\n",
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" # One zero\n",
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" if count == 1:\n",
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" result = seen[index + 1] + seen[index - 1] + 1\n",
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" # Multiple zeroes\n",
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" else:\n",
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" result = max(seen[index + 1], seen[index - 1]) + 1\n",
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" if result > max_result:\n",
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" max_result = result\n",
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" looking_for = not looking_for\n",
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" return max_result"
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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": "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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"Overwriting test_flip_bit.py\n"
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]
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}
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],
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"source": [
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"%%writefile test_flip_bit.py\n",
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"from nose.tools import assert_equal, assert_raises\n",
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"\n",
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"\n",
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"class TestBits(object):\n",
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"\n",
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" def test_flip_bit(self):\n",
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" bits = Bits()\n",
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" assert_raises(TypeError, bits.flip_bit, None)\n",
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" assert_equal(bits.flip_bit(0), 1)\n",
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" assert_equal(bits.flip_bit(-1), bits.MAX_BITS)\n",
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" num = int('00001111110111011110001111110000', base=2)\n",
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" expected = 10\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
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" num = int('00000100111011101111100011111011', base=2)\n",
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" expected = 9\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
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" num = int('00010011101110111110001111101111', base=2)\n",
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" expected = 10\n",
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" assert_equal(bits.flip_bit(num), expected)\n",
|
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" print('Success: test_print_binary')\n",
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"\n",
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"\n",
|
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"def main():\n",
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" test = TestBits()\n",
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" test.test_flip_bit()\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": "code",
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"execution_count": 3,
|
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"metadata": {
|
||||
"collapsed": false
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},
|
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"outputs": [
|
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{
|
||||
"name": "stdout",
|
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"output_type": "stream",
|
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"text": [
|
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"Success: test_print_binary\n"
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]
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}
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],
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"source": [
|
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"%run -i test_flip_bit.py"
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]
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}
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],
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"metadata": {
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"kernelspec": {
|
||||
"display_name": "Python 3",
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"language": "python",
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||||
"name": "python3"
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||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
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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",
|
||||
"pygments_lexer": "ipython3",
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||||
"version": "3.4.3"
|
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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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29
bit_manipulation/flip_bit/test_flip_bit.py
Normal file
29
bit_manipulation/flip_bit/test_flip_bit.py
Normal file
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@ -0,0 +1,29 @@
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from nose.tools import assert_equal, assert_raises
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class TestBits(object):
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def test_flip_bit(self):
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bits = Bits()
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assert_raises(TypeError, bits.flip_bit, None)
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assert_equal(bits.flip_bit(0), 1)
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assert_equal(bits.flip_bit(-1), bits.MAX_BITS)
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num = int('00001111110111011110001111110000', base=2)
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expected = 10
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assert_equal(bits.flip_bit(num), expected)
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num = int('00000100111011101111100011111011', base=2)
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expected = 9
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assert_equal(bits.flip_bit(num), expected)
|
||||
num = int('00010011101110111110001111101111', base=2)
|
||||
expected = 10
|
||||
assert_equal(bits.flip_bit(num), expected)
|
||||
print('Success: test_print_binary')
|
||||
|
||||
|
||||
def main():
|
||||
test = TestBits()
|
||||
test.test_flip_bit()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Loading…
Reference in New Issue
Block a user