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   "source": [
    "## the problem is that implement queue with the enqueue() and dequeue() operations with stacks"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Queue:\n",
    "    \n",
    "    def __init__(self):\n",
    "        self.dequeue_stack = []\n",
    "        self.enqueue_stack = []\n",
    "        \n",
    "    def enqueue(self, data):\n",
    "        self.enqueue_stack.append(data)\n",
    "        \n",
    "    def dequeue(self):\n",
    "        if not self.enqueue_stack and not self.dequeue_stack:\n",
    "            raise Exception('Stacks are empty')\n",
    "        \n",
    "        # if dequeue stack is empty, add all item\n",
    "        if not self.dequeue_stack:\n",
    "            while self.enqueue_stack:\n",
    "                self.dequeue_stack.append(self.enqueue_stack.pop())\n",
    "                \n",
    "        return self.dequeue_stack.pop()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "q = Queue()\n",
    "q.enqueue(1)\n",
    "q.enqueue(2)\n",
    "q.enqueue(3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "q.dequeue()"
   ]
  }
 ],
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