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changed solutions to challenge Arrays & Strings - Permutations: #234

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changed solutions to challenge Arrays & Strings - Permutations: #234

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7 changes: 4 additions & 3 deletions arrays_strings/permutation/permutation_challenge.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,7 @@
" def test_permutation(self, func):\n",
" assert_equal(func(None, 'foo'), False)\n",
" assert_equal(func('', 'foo'), False)\n",
" assert_equal(func('', ''), False)\n",
" assert_equal(func('Nib', 'bin'), False)\n",
" assert_equal(func('act', 'cat'), True)\n",
" assert_equal(func('a ct', 'ca t'), True)\n",
Expand Down Expand Up @@ -159,7 +160,7 @@
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"display_name": "Python [default]",
"language": "python",
"name": "python3"
},
Expand All @@ -173,9 +174,9 @@
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.5.0"
"version": "3.6.3"
}
},
"nbformat": 4,
"nbformat_minor": 0
"nbformat_minor": 2
}
71 changes: 62 additions & 9 deletions arrays_strings/permutation/permutation_solution.ipynb
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,7 @@
},
{
"cell_type": "code",
"execution_count": 1,
"execution_count": 21,
"metadata": {
"collapsed": false
},
Expand All @@ -99,7 +99,7 @@
"class Permutations(object):\n",
"\n",
" def is_permutation(self, str1, str2):\n",
" if str1 is None or str2 is None:\n",
" if not str1 or not str2:\n",
" return False\n",
" return sorted(str1) == sorted(str2)"
]
Expand Down Expand Up @@ -141,7 +141,7 @@
},
{
"cell_type": "code",
"execution_count": 2,
"execution_count": 24,
"metadata": {
"collapsed": false
},
Expand All @@ -153,7 +153,7 @@
"class PermutationsAlt(object):\n",
"\n",
" def is_permutation(self, str1, str2):\n",
" if str1 is None or str2 is None:\n",
" if not str1 or not str2:\n",
" return False\n",
" if len(str1) != len(str2):\n",
" return False\n",
Expand All @@ -166,6 +166,55 @@
" return unique_counts1 == unique_counts2"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Algorithm: Array Removal\n",
" \n",
"Since a permuation is a symmetric relation (A is a permutation of B iff B is a permutation of A) one only needs to check if one can rebuild the first string using all the characters of the second.\n",
"\n",
"Steps:\n",
"* Check if the strings are not None or empty\n",
"* Turn the second string into a list of characters\n",
"* For each character in the first string:\n",
" * If the character does not appear in the list, return False\n",
" * Else: remove the character from the list\n",
"* Return True if the list is empty (we used up all characters), else return False\n",
"\n",
"Complexity:\n",
"* Time: O(n)\n",
"* Space: O(n)"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Code: Array Lookup"
]
},
{
"cell_type": "code",
"execution_count": 39,
"metadata": {},
"outputs": [],
"source": [
"class PermutationsArray(object):\n",
"\n",
" def is_permutation(self, str1, str2):\n",
" if not str1 or not str2:\n",
" return False\n",
" \n",
" chars = list(str2) \n",
" for char in str1:\n",
" if char not in chars:\n",
" return False\n",
" else:\n",
" chars.remove(char)\n",
" return len(chars) == 0"
]
},
{
"cell_type": "markdown",
"metadata": {},
Expand All @@ -175,7 +224,7 @@
},
{
"cell_type": "code",
"execution_count": 3,
"execution_count": 40,
"metadata": {
"collapsed": false
},
Expand All @@ -198,6 +247,7 @@
" def test_permutation(self, func):\n",
" assert_equal(func(None, 'foo'), False)\n",
" assert_equal(func('', 'foo'), False)\n",
" assert_equal(func('', ''), False)\n",
" assert_equal(func('Nib', 'bin'), False)\n",
" assert_equal(func('act', 'cat'), True)\n",
" assert_equal(func('a ct', 'ca t'), True)\n",
Expand All @@ -212,6 +262,8 @@
" try:\n",
" permutations_alt = PermutationsAlt()\n",
" test.test_permutation(permutations_alt.is_permutation)\n",
" permutations_array = PermutationsArray()\n",
" test.test_permutation(permutations_array.is_permutation)\n",
" except NameError:\n",
" # Alternate solutions are only defined\n",
" # in the solutions file\n",
Expand All @@ -224,7 +276,7 @@
},
{
"cell_type": "code",
"execution_count": 4,
"execution_count": 41,
"metadata": {
"collapsed": false
},
Expand All @@ -233,6 +285,7 @@
"name": "stdout",
"output_type": "stream",
"text": [
"Success: test_permutation\n",
"Success: test_permutation\n",
"Success: test_permutation\n"
]
Expand All @@ -245,7 +298,7 @@
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"display_name": "Python [default]",
"language": "python",
"name": "python3"
},
Expand All @@ -259,9 +312,9 @@
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.5.0"
"version": "3.6.3"
}
},
"nbformat": 4,
"nbformat_minor": 0
"nbformat_minor": 2
}
3 changes: 3 additions & 0 deletions arrays_strings/permutation/test_permutation_solution.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ class TestPermutation(object):
def test_permutation(self, func):
assert_equal(func(None, 'foo'), False)
assert_equal(func('', 'foo'), False)
assert_equal(func('', ''), False)
assert_equal(func('Nib', 'bin'), False)
assert_equal(func('act', 'cat'), True)
assert_equal(func('a ct', 'ca t'), True)
Expand All @@ -20,6 +21,8 @@ def main():
try:
permutations_alt = PermutationsAlt()
test.test_permutation(permutations_alt.is_permutation)
permutations_array = PermutationsArray()
test.test_permutation(permutations_array.is_permutation)
except NameError:
# Alternate solutions are only defined
# in the solutions file
Expand Down