interactive-coding-challenges/sorting-searching/insertion-sort.ipynb
2015-05-29 06:08:15 -04:00

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"## Problem: Implement insertion sort.\n",
"\n",
"* [Clarifying Questions](#Clarifying-Questions)\n",
"* [Test Cases](#Test-Cases)\n",
"* [Algorithm](#Algorithm)\n",
"* [Code](#Code)\n",
"* [Pythonic-Code](#Pythonic-Code)"
]
},
{
"cell_type": "markdown",
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"source": [
"## Clarifying Questions\n",
"\n",
"* None"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Test Cases\n",
"\n",
"* Empty input\n",
"* One element\n",
"* Two or more elements"
]
},
{
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"source": [
"## Algorithm\n",
"\n",
"Wikipedia's animation:\n",
"![alt text](http://upload.wikimedia.org/wikipedia/commons/0/0f/Insertion-sort-example-300px.gif)\n",
"\n",
"* For each value index 1 to n - 1\n",
" * Compare with all elements to the left of the current value to determine new insertion point\n",
" * Hold current value in temp variable\n",
" * Shift elements from new insertion point right\n",
" * Insert value in temp variable\n",
" * Break\n",
"\n",
"Complexity:\n",
"* Time: O(n^2) avarage, worst. O(1) best if input is already sorted.\n",
"* Space: O(1), stable"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Code"
]
},
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"source": [
"def insertion_sort(data):\n",
" if len(data) < 2:\n",
" return\n",
" for r in xrange(1, len(data)):\n",
" for l in xrange(0, r):\n",
" if data[l] > data[r]:\n",
" temp = data[r]\n",
" data[l+1:r+1] = data[l:r]\n",
" data[l] = temp\n",
" break"
]
},
{
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"print('Empty input')\n",
"data = []\n",
"insertion_sort(data)\n",
"print(data)\n",
"print('One element')\n",
"data = [5]\n",
"insertion_sort(data)\n",
"print(data)\n",
"print('Two or more elements')\n",
"data = [5, 1, 7, 2, 6, -3, 5, 7, -1]\n",
"insertion_sort(data)\n",
"print(data)"
]
}
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