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

25
sorting_searching/merge_sort/merge_sort_solution.ipynb
View File

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