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Update hanoi challenge (#121)

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Update constraints and test cases.  Move implementation to a class.  Update tests.
This commit is contained in:
Donne Martin
2016-11-19 09:01:44 -05:00
committed by GitHub
parent 14de5e4233
commit 430cca2a01
3 changed files with 70 additions and 52 deletions
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58
recursion_dynamic/hanoi/hanoi_solution.ipynb
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@@ -34,6 +34,10 @@
"## Constraints\n",
"\n",
"* Can we assume we already have a stack class that can be used for this problem?\n",
" * Yes\n",
"* Can we assume the inputs are valid?\n",
" * No\n",
"* Can we assume this fits memory?\n",
" * Yes"
]
},
@@ -43,8 +47,8 @@
"source": [
"## Test Cases\n",
"\n",
"* None tower(s)\n",
"* 0 disks\n",
"* None tower(s) -> Exception\n",
"* 0 disks -> None\n",
"* 1 disk\n",
"* 2 or more disks"
]
@@ -93,14 +97,19 @@
},
"outputs": [],
"source": [
"def hanoi(num_disks, src, dest, buff):\n",
" if src is None or dest is None or buff is None:\n",
" return\n",
" if num_disks > 0:\n",
" hanoi(num_disks-1, src, buff, dest)\n",
" data = src.pop()\n",
" dest.push(data)\n",
" hanoi(num_disks-1, buff, dest, src)"
"class Hanoi(object):\n",
"\n",
" def move_disks(self, num_disks, src, dest, buff):\n",
" if src is None or dest is None or buff is None:\n",
" raise TypeError('Cannot have a None input')\n",
" self._move_disks(num_disks, src, dest, buff)\n",
"\n",
" def _move_disks(self, num_disks, src, dest, buff):\n",
" if num_disks == 0:\n",
" return\n",
" self.move_disks(num_disks-1, src, buff, dest)\n",
" dest.push(src.pop())\n",
" self.move_disks(num_disks-1, buff, dest, src)"
]
},
{
@@ -128,35 +137,36 @@
],
"source": [
"%%writefile test_hanoi.py\n",
"from nose.tools import assert_equal\n",
"from nose.tools import assert_equal, assert_raises\n",
"\n",
"\n",
"class TestHanoi(object):\n",
"\n",
" def test_hanoi(self):\n",
" hanoi = Hanoi()\n",
" num_disks = 3\n",
" src = Stack()\n",
" buff = Stack()\n",
" dest = Stack()\n",
"\n",
" print('Test: None towers')\n",
" hanoi(num_disks, None, None, None)\n",
" assert_raises(TypeError, hanoi.move_disks, num_disks, None, None, None)\n",
"\n",
" print('Test: 0 disks')\n",
" hanoi(num_disks, src, dest, buff)\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" assert_equal(dest.pop(), None)\n",
"\n",
" print('Test: 1 disk')\n",
" src.push(5)\n",
" hanoi(num_disks, src, dest, buff)\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" assert_equal(dest.pop(), 5)\n",
"\n",
" print('Test: 2 or more disks')\n",
" for i in range(num_disks, -1, -1):\n",
" src.push(i)\n",
" hanoi(num_disks, src, dest, buff)\n",
" for i in range(0, num_disks):\n",
" assert_equal(dest.pop(), i)\n",
" for disk_index in range(num_disks, -1, -1):\n",
" src.push(disk_index)\n",
" hanoi.move_disks(num_disks, src, dest, buff)\n",
" for disk_index in range(0, num_disks):\n",
" assert_equal(dest.pop(), disk_index)\n",
"\n",
" print('Success: test_hanoi')\n",
"\n",
@@ -196,21 +206,21 @@
],
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"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",
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