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Updated unit test to use nose and moved it to Test Cases section. Tweaked algorithm description.

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Donne Martin 2015-06-20 19:44:27 -04:00
parent 83e3eedb52
commit 4d1b78617a
1 changed files with 38 additions and 16 deletions
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54
arrays-strings/replace_char.ipynb
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@ -38,21 +38,51 @@
"source": [
"## Test Cases\n",
"\n",
"* NULL\n",
"* NULL->NULL\n",
"* ' ' -> '%20'\n",
"* ' foo bar ' -> '%20foo%20bar%20'\n",
"* 'foo' -> 'foo'"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"collapsed": true
},
"outputs": [],
"source": [
"from nose.tools import assert_equal\n",
"\n",
"class Test(object):\n",
" def test_replace_char(self, func):\n",
" str0 = None\n",
" str1 = bytearray(' ||')\n",
" str2 = bytearray(' foo bar ||||||')\n",
" str3 = bytearray('foo')\n",
" encode_spaces(str0, 0)\n",
" encode_spaces(str1, 1)\n",
" encode_spaces(str2, 9)\n",
" encode_spaces(str3, 3)\n",
" assert_equal(str0, None)\n",
" assert_equal(str1, '%20')\n",
" assert_equal(str2, '%20foo%20bar%20')\n",
" assert_equal(str3, 'foo')\n",
"\n",
"def run_tests(func):\n",
" test = Test()\n",
" test.test_replace_char(func)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm\n",
"\n",
"![alt text](https://raw.githubusercontent.com/donnemartin/algorithms-data-structures/master/images/replace_string.jpg)\n",
"Since Python strings are immutable, we'll use a bytearray instead to exercise in-place string manipulation as you would get with a C string (which is null terminated, as seen in the diagram below). For the python bytearray we will not use a null terminator.\n",
"\n",
"Since Python strings are immutable, we'll use a bytearray instead to exercise in-place string manipulation as you would get with a C string (which is null terminated, as seen in the above diagram). For the python bytearray we will not use a null terminator.\n",
"![alt text](https://raw.githubusercontent.com/donnemartin/algorithms-data-structures/master/images/replace_string.jpg)\n",
"\n",
"* Count the number of spaces in the bytearray\n",
"* Determine the new bytearray length\n",
@ -101,18 +131,7 @@
" string[new_length] = string[i]\n",
" new_length -= 1\n",
"\n",
"str0 = None\n",
"str1 = bytearray(' ||')\n",
"str2 = bytearray(' foo bar ||||||')\n",
"str3 = bytearray('foo')\n",
"encode_spaces(str0, 0)\n",
"encode_spaces(str1, 1)\n",
"encode_spaces(str2, 9)\n",
"encode_spaces(str3, 3)\n",
"print(str0)\n",
"print(str1)\n",
"print(str2)\n",
"print(str3)"
"run_tests(encode_spaces)"
]
},
{
@ -138,7 +157,10 @@
" return re.sub(' ', '%20', string)\n",
"\n",
"def encode_spaces_alt2(string):\n",
" return string.replace(' ', '%20')"
" return string.replace(' ', '%20')\n",
"\n",
"run_tests(encode_spaces_alt)\n",
"run_tests(encode_spaces_alt2)"
]
}
],