Solution for Google's phone interview 2021 (Python)

google_phone_interview_2021.ipynb

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   "source": [
    "# Google phone interview 2021"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Implement the `GooglePhotos` Python 3 class. Where `ack()` method (acknowledge) register an ID, if the ID is the new and higher than `first_id`. The `unask_id()` method will return the first available ID.\n",
    "```python\n",
    "class GooglePhotos:\n",
    "\n",
    "    def __init__(self, first_id):\n",
    "        pass\n",
    "\n",
    "    def ack(self, photo_id):\n",
    "        pass\n",
    "\n",
    "    def unack_id(self):\n",
    "        pass\n",
    "```\n",
    "\n",
    "Example:\n",
    "```python\n",
    "client = GooglePhotos(first_id=100)\n",
    "client.ack(101)\n",
    "client.unack_id()  --> 102\n",
    "```"
   ]
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   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "class GooglePhotos:\n",
    "\n",
    "    def __init__(self, first_id):\n",
    "        self.first_id = first_id\n",
    "        self.register = []\n",
    "        self.register.append(first_id)\n",
    "\n",
    "    def ack(self, photo_id):\n",
    "        if (photo_id > self.first_id) and (photo_id not in self.register):\n",
    "            self.register.append(photo_id)\n",
    "\n",
    "    def unack_id(self):\n",
    "        for i in range(self.first_id, max(self.register)+2):\n",
    "            if i not in self.register:\n",
    "                return i"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[2]"
      ]
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     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "client = GooglePhotos(first_id=2)\n",
    "client.register"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.unack_id()  # 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[2]"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.ack(1)\n",
    "client.register"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.unack_id()  # 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "client.ack(3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.unack_id()  # 4"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[2, 3, 5]"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.ack(5)\n",
    "client.register"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.unack_id()  # 4"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[2, 3, 5, 4, 6]"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.ack(4)\n",
    "client.ack(5)\n",
    "client.ack(6)\n",
    "client.register"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "7"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "client.unack_id()  # 7"
   ]
  }
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