University-of-Toronto-Crafting-Quality-Code/Lesson 1 Notes.ipynb

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    "##Algorithm for Palindromes"
   ]
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    "def is_palindrome_v1(s):\n",
    "    \n",
    "    \"\"\"(str)-> bool\n",
    "    \n",
    "    return True if and only if s is a palindrome\n",
    "    \n",
    "    >>> is_palindrome_v1('noon')\n",
    "    True\n",
    "    >>> is_palindrome_v1('nosxon')\n",
    "    False\n",
    "    \"\"\"\n",
    "    return reverse(s) == s\n",
    "    \n",
    "def reverse():\n",
    "    rev = \"\"       ##The point of this one was a simple, reconstruct the reverse of the string, then compare\n",
    "    \n",
    "    for ch in s:\n",
    "        rev = ch + rev\n",
    "    return rev\n",
    "\n",
    "def is_palindrome_v2(s):\n",
    "    \n",
    "    \"\"\"(str)-> bool\n",
    "    \n",
    "    return True if and only if s is a palindrome\n",
    "    \n",
    "    >>> is_palindrome_v1('noon')\n",
    "    True\n",
    "    >>> is_palindrome_v1('nosxon')\n",
    "    False\n",
    "    \"\"\"   \n",
    "    \n",
    "    ##IN this instance, we compare the FIRST half to the SECOND Half\n",
    "    n = len(s)\n",
    "    return s[:n//2] == reverse(s[n-n//2:])\n",
    "    \n",
    "def is_palindrome_v3(s):\n",
    "    \n",
    "    \"\"\"(str)-> bool\n",
    "    \n",
    "    return True if and only if s is a palindrome\n",
    "    \n",
    "    >>> is_palindrome_v1('noon')\n",
    "    True\n",
    "    >>> is_palindrome_v1('nosxon')\n",
    "    False\n",
    "    \"\"\"\n",
    "    ##in this instance, we are moving TOWARDS the cetre\n",
    "    i = 0\n",
    "    j = len(s) - 1 \n",
    "    \n",
    "    while i < j and s[i] == s[j]:\n",
    "        i = i + 1\n",
    "        j = j -1\n",
    "        \n",
    "    return j <= 1"
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   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "## Restaurant notes\n",
    "\"\"\"\n",
    "Make notes on what is in the data\n",
    "\"\"\"\n",
    "6 8 9 12\n"
   ]
  }
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