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Polish merge sort challenge and solution

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Add None input test case.  Update space complexity discussion.
This commit is contained in:
Donne Martin 2016-02-26 06:52:54 -05:00
parent 15ed55a7d4
commit 56f8ea1e74
3 changed files with 33 additions and 13 deletions
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16
sorting_searching/merge_sort/merge_sort_challenge.ipynb
View File

@ -44,6 +44,7 @@
"source": [
"## Test Cases\n",
"\n",
"* None -> None\n",
"* Empty input -> []\n",
"* One element -> [element]\n",
"* Two or more elements\n",
@ -104,6 +105,11 @@
"\n",
"class TestMergeSort(object):\n",
" def test_merge_sort(self):\n",
" print('None input')\n",
" data = None\n",
" sorted_data = merge_sort(data)\n",
" assert_equal(sorted_data, None)\n",
"\n",
" print('Empty input')\n",
" data = []\n",
" sorted_data = merge_sort(data)\n",
@ -143,21 +149,21 @@
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"display_name": "Python 3",
"language": "python",
"name": "python2"
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
"pygments_lexer": "ipython3",
"version": "3.4.3"
}
},
"nbformat": 4,

25
sorting_searching/merge_sort/merge_sort_solution.ipynb
View File

@ -43,6 +43,7 @@
"source": [
"## Test Cases\n",
"\n",
"* None -> None\n",
"* Empty input -> []\n",
"* One element -> [element]\n",
"* Two or more elements\n",
@ -68,7 +69,9 @@
"\n",
"Complexity:\n",
"* Time: O(n log(n))\n",
"* Space: O(n), stable"
"* Space: O(n+m), n = number of elements, m = recursion depth\n",
"\n",
"Most implementations are stable."
]
},
{
@ -112,11 +115,11 @@
"\n",
"\n",
"def merge_sort(data):\n",
" if len(data) < 2:\n",
" if data is None or len(data) < 2:\n",
" return data\n",
" mid = len(data) // 2\n",
" left = data[0:mid]\n",
" right = data[mid:len(data)]\n",
" right = data[mid:]\n",
" left = merge_sort(left)\n",
" right = merge_sort(right)\n",
" return merge(left, right)"
@ -152,6 +155,11 @@
"\n",
"class TestMergeSort(object):\n",
" def test_merge_sort(self):\n",
" print('None input')\n",
" data = None\n",
" sorted_data = merge_sort(data)\n",
" assert_equal(sorted_data, None)\n",
"\n",
" print('Empty input')\n",
" data = []\n",
" sorted_data = merge_sort(data)\n",
@ -190,6 +198,7 @@
"name": "stdout",
"output_type": "stream",
"text": [
"None input\n",
"Empty input\n",
"One element\n",
"Two or more elements\n",
@ -204,21 +213,21 @@
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"display_name": "Python 3",
"language": "python",
"name": "python2"
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.10"
"pygments_lexer": "ipython3",
"version": "3.4.3"
}
},
"nbformat": 4,

5
sorting_searching/merge_sort/test_merge_sort.py
View File

@ -3,6 +3,11 @@ from nose.tools import assert_equal
class TestMergeSort(object):
def test_merge_sort(self):
print('None input')
data = None
sorted_data = merge_sort(data)
assert_equal(sorted_data, None)
print('Empty input')
data = []
sorted_data = merge_sort(data)