234. Palindrome Linked List.ipynb

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   "source": [
    "Given a singly linked list, determine if it is a palindrome.\n",
    "\n",
    "Follow up:\n",
    "Could you do it in O(n) time and O(1) space?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
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   "outputs": [],
   "source": [
    "class ListNode(object):\n",
    "    def __init__(self, x):\n",
    "        self.val = x\n",
    "        self.next = None\n",
    "\n",
    "class Solution(object):\n",
    "    def isPalindrome(self, head):\n",
    "        \"\"\"\n",
    "        :type head: ListNode\n",
    "        :rtype: bool\n",
    "        \"\"\"\n",
    "        \n",
    "            \n",
    "        def rev(head):\n",
    "            dum=ListNode(0)\n",
    "            p=head\n",
    "            while p:\n",
    "                temp=p.next\n",
    "                p.next=dum.next\n",
    "                dum.next=p\n",
    "                p=temp\n",
    "            return dum.next\n",
    "        s=head\n",
    "        f=head\n",
    "        while f and f.next:\n",
    "            s=s.next\n",
    "            f=f.next.next\n",
    "        n=rev(s)\n",
    "        m=n\n",
    "        t=head\n",
    "        while m:\n",
    "            if t.val!=m.val:\n",
    "                return False\n",
    "            t=t.next\n",
    "            m=m.next\n",
    "        return True\n",
    "                "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
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     "execution_count": 12,
     "metadata": {},
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   "source": [
    "l1=ListNode(1)\n",
    "l2=ListNode(2)\n",
    "l3=ListNode(1)\n",
    "l1=ListNode(1)\n",
    "l1=ListNode(1)\n",
    "l1=ListNode(1)\n",
    "l1.next=l2\n",
    "l2.next=l3\n",
    "s=Solution()\n",
    "s.isPalindrome(l1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
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   "outputs": [],
   "source": [
    "s1=\"abc\"\n",
    "s2=\"cba\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "a\n",
      "b\n",
      "c\n"
     ]
    }
   ],
   "source": [
    "for c in s1:\n",
    "    print(s)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ord('a')^ord('b')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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