mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
Add two sum challenge
This commit is contained in:
Donne Martin
parent
6c507fc3ea
commit
1112520784
0
arrays_strings/two_sum/__init__.py
Normal file
0
arrays_strings/two_sum/__init__.py
Normal file
23
arrays_strings/two_sum/test_two_sum.py
Normal file
23
arrays_strings/two_sum/test_two_sum.py
Normal file
@ -0,0 +1,23 @@
|
||||
from nose.tools import assert_equal, assert_raises
|
||||
|
||||
|
||||
class TestTwoSum(object):
|
||||
|
||||
def test_two_sum(self):
|
||||
solution = Solution()
|
||||
assert_raises(TypeError, solution.two_sum, None, None)
|
||||
assert_raises(ValueError, solution.two_sum, [], 0)
|
||||
target = 7
|
||||
nums = [1, 3, 2, -7, 5]
|
||||
expected = [2, 4]
|
||||
assert_equal(solution.two_sum(nums, target), expected)
|
||||
print('Success: test_two_sum')
|
||||
|
||||
|
||||
def main():
|
||||
test = TestTwoSum()
|
||||
test.test_two_sum()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
170
arrays_strings/two_sum/two_sum_challenge.ipynb
Normal file
170
arrays_strings/two_sum/two_sum_challenge.ipynb
Normal file
@ -0,0 +1,170 @@
|
||||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"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)."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Challenge Notebook"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Problem: Given an array, find the two indices that sum to a specific value.\n",
|
||||
"\n",
|
||||
"* [Constraints](#Constraints)\n",
|
||||
"* [Test Cases](#Test-Cases)\n",
|
||||
"* [Algorithm](#Algorithm)\n",
|
||||
"* [Code](#Code)\n",
|
||||
"* [Unit Test](#Unit-Test)\n",
|
||||
"* [Solution Notebook](#Solution-Notebook)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Constraints\n",
|
||||
"\n",
|
||||
"* Is there exactly one solution?\n",
|
||||
" * Yes\n",
|
||||
"* Is there always a solution?\n",
|
||||
" * Yes\n",
|
||||
"* Is the array an array of ints?\n",
|
||||
" * Yes\n",
|
||||
"* Is the array sorted?\n",
|
||||
" No\n",
|
||||
"* Are negative values possible?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume the inputs are valid?\n",
|
||||
" * No\n",
|
||||
"* Can we assume this fits memory?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"* None input -> TypeError\n",
|
||||
"* [] -> ValueError\n",
|
||||
"* [1, 3, 2, -7, 5], 7 -> [2, 4]"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Algorithm\n",
|
||||
"\n",
|
||||
"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."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Code"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"class Solution(object):\n",
|
||||
"\n",
|
||||
" def two_sum(self, val):\n",
|
||||
" # TODO: Implement me\n",
|
||||
" pass"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Unit Test"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"**The following unit test is expected to fail until you solve the challenge.**"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": null,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"# %load test_two_sum.py\n",
|
||||
"from nose.tools import assert_equal, assert_raises\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestTwoSum(object):\n",
|
||||
"\n",
|
||||
" def test_two_sum(self):\n",
|
||||
" solution = Solution()\n",
|
||||
" assert_raises(TypeError, solution.two_sum, None)\n",
|
||||
" assert_equal(solution.two_sum(0), 0)\n",
|
||||
" print('Success: test_two_sum')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestTwoSum()\n",
|
||||
" test.test_two_sum()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Solution Notebook\n",
|
||||
"\n",
|
||||
"Review the [Solution Notebook]() for a discussion on algorithms and code solutions."
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 3",
|
||||
"language": "python",
|
||||
"name": "python3"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.5.0"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
271
arrays_strings/two_sum/two_sum_solution.ipynb
Normal file
271
arrays_strings/two_sum/two_sum_solution.ipynb
Normal file
@ -0,0 +1,271 @@
|
||||
{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"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)."
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Solution Notebook"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Problem: Given an array, find the two indices that sum to a specific value.\n",
|
||||
"\n",
|
||||
"* [Constraints](#Constraints)\n",
|
||||
"* [Test Cases](#Test-Cases)\n",
|
||||
"* [Algorithm](#Algorithm)\n",
|
||||
"* [Code](#Code)\n",
|
||||
"* [Unit Test](#Unit-Test)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Constraints\n",
|
||||
"\n",
|
||||
"* Is there exactly one solution?\n",
|
||||
" * Yes\n",
|
||||
"* Is there always a solution?\n",
|
||||
" * Yes\n",
|
||||
"* Is the array an array of ints?\n",
|
||||
" * Yes\n",
|
||||
"* Is the array sorted?\n",
|
||||
" No\n",
|
||||
"* Are negative values possible?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume the inputs are valid?\n",
|
||||
" * No\n",
|
||||
"* Can we assume this fits memory?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"* None input -> TypeError\n",
|
||||
"* [] -> ValueError\n",
|
||||
"* [1, 3, 2, -7, 5], 7 -> [2, 4]"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Algorithm\n",
|
||||
"\n",
|
||||
"### Brute force\n",
|
||||
"\n",
|
||||
"* For i in range(len(input)):\n",
|
||||
" * For j in range(i+1, len(input)):\n",
|
||||
" * if i + j == target return True\n",
|
||||
"* return False\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(n^2)\n",
|
||||
"* Space: O(1)\n",
|
||||
"\n",
|
||||
"### Optimized\n",
|
||||
"\n",
|
||||
"<pre>\n",
|
||||
"* Loop through each num in nums\n",
|
||||
" * Calculate the cache_target = target - num\n",
|
||||
"\n",
|
||||
"target = 7\n",
|
||||
"index = 0 1 2 3 4\n",
|
||||
"nums = [1, 3, 2, -7, 5]\n",
|
||||
" ^\n",
|
||||
"cache_target = 7 - 1 = 6\n",
|
||||
"cache\n",
|
||||
"6 -> 0\n",
|
||||
"\n",
|
||||
"1 not in cache\n",
|
||||
"\n",
|
||||
"index = 0 1 2 3 4\n",
|
||||
"nums = [1, 3, 2, -7, 5]\n",
|
||||
" ^\n",
|
||||
"cache_target = 7 - 3 = 4\n",
|
||||
"cache\n",
|
||||
"6 -> 0\n",
|
||||
"4 -> 1\n",
|
||||
"\n",
|
||||
"3 not in cache\n",
|
||||
"\n",
|
||||
"index = 0 1 2 3 4\n",
|
||||
"nums = [1, 3, 2, -7, 5]\n",
|
||||
" ^\n",
|
||||
"cache_target = 7 - 2 = 5\n",
|
||||
"cache\n",
|
||||
"6 -> 0\n",
|
||||
"4 -> 1\n",
|
||||
"5 -> 2\n",
|
||||
"\n",
|
||||
"2 not in cache\n",
|
||||
"\n",
|
||||
"index = 0 1 2 3 4\n",
|
||||
"nums = [1, 3, 2, -7, 5]\n",
|
||||
" ^\n",
|
||||
"cache_target = 7 + 7 = 14\n",
|
||||
"cache\n",
|
||||
"6 -> 0\n",
|
||||
"4 -> 1\n",
|
||||
"5 -> 2\n",
|
||||
"14 -> 3\n",
|
||||
"\n",
|
||||
"-7 not in cache\n",
|
||||
"\n",
|
||||
"index = 0 1 2 3 4\n",
|
||||
"nums = [1, 3, 2, -7, 5]\n",
|
||||
" ^\n",
|
||||
"cache_target = 7 - 5 = 2\n",
|
||||
"cache\n",
|
||||
"6 -> 0\n",
|
||||
"4 -> 1\n",
|
||||
"5 -> 2\n",
|
||||
"14 -> 3\n",
|
||||
"\n",
|
||||
"5 in cache, success, output matching indices: cache[num] and current iteration index\n",
|
||||
"\n",
|
||||
"output = [2, 4]\n",
|
||||
"</pre>\n",
|
||||
"\n",
|
||||
"Complexity:\n",
|
||||
"* Time: O(n)\n",
|
||||
"* Space: O(n)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Code"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 1,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"class Solution(object):\n",
|
||||
"\n",
|
||||
" def two_sum(self, nums, target):\n",
|
||||
" if nums is None or target is None:\n",
|
||||
" raise TypeError('nums or target cannot be None')\n",
|
||||
" if not nums:\n",
|
||||
" raise ValueError('nums cannot be empty')\n",
|
||||
" cache = {}\n",
|
||||
" for index, num in enumerate(nums):\n",
|
||||
" cache_target = target - num\n",
|
||||
" if num in cache:\n",
|
||||
" return [cache[num], index]\n",
|
||||
" else:\n",
|
||||
" cache[cache_target] = index\n",
|
||||
" return None"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Unit Test"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 2,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Overwriting test_two_sum.py\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%%writefile test_two_sum.py\n",
|
||||
"from nose.tools import assert_equal, assert_raises\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestTwoSum(object):\n",
|
||||
"\n",
|
||||
" def test_two_sum(self):\n",
|
||||
" solution = Solution()\n",
|
||||
" assert_raises(TypeError, solution.two_sum, None, None)\n",
|
||||
" assert_raises(ValueError, solution.two_sum, [], 0)\n",
|
||||
" target = 7\n",
|
||||
" nums = [1, 3, 2, -7, 5]\n",
|
||||
" expected = [2, 4]\n",
|
||||
" assert_equal(solution.two_sum(nums, target), expected)\n",
|
||||
" print('Success: test_two_sum')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestTwoSum()\n",
|
||||
" test.test_two_sum()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 3,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Success: test_two_sum\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%run -i test_two_sum.py"
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 3",
|
||||
"language": "python",
|
||||
"name": "python3"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.5.0"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
Loading…
x
Reference in New Issue
Block a user