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   "source": [
    "# 17-17 · Победа, ничья и terminal state\n",
    "\n",
    "Практика к разделу [«Победа, ничья и terminal state»](../../site/chapters/glava-17/17-17-pobeda-nichya-terminal.html)."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "59a9829f",
   "metadata": {},
   "source": [
    "## Цель\n",
    "\n",
    "Убедиться, что победа на последнем ходу не превращается в ложную ничью."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2662548d",
   "metadata": {},
   "source": [
    "## Рабочий пример"
   ]
  },
  {
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   "execution_count": 1,
   "id": "486eb5d2",
   "metadata": {
    "execution": {
     "iopub.execute_input": "2026-09-03T10:12:59.002825Z",
     "iopub.status.busy": "2026-09-03T10:12:59.002698Z",
     "iopub.status.idle": "2026-09-03T10:12:59.022988Z",
     "shell.execute_reply": "2026-09-03T10:12:59.022474Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Ничья: True\n"
     ]
    }
   ],
   "source": [
    "WINNING_LINES = (\n",
    "    (0, 1, 2), (3, 4, 5), (6, 7, 8),\n",
    "    (0, 3, 6), (1, 4, 7), (2, 5, 8),\n",
    "    (0, 4, 8), (2, 4, 6),\n",
    ")\n",
    "\n",
    "def find_winner(board):\n",
    "    for a, b, c in WINNING_LINES:\n",
    "        mark = board[a]\n",
    "        if mark and mark == board[b] == board[c]:\n",
    "            return mark, (a, b, c)\n",
    "    return None, None\n",
    "\n",
    "def is_draw(board):\n",
    "    winner, _ = find_winner(board)\n",
    "    return winner is None and all(board)\n",
    "\n",
    "nichya = [\"X\", \"O\", \"X\", \"X\", \"O\", \"O\", \"O\", \"X\", \"X\"]\n",
    "print(\"Ничья:\", is_draw(nichya))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e8e2bea9",
   "metadata": {},
   "source": [
    "## Задание ★★ Самостоятельная задача — победа побеждает ничью"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "f1d61226",
   "metadata": {
    "execution": {
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     "iopub.status.busy": "2026-09-03T10:12:59.024128Z",
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     "shell.execute_reply": "2026-09-03T10:12:59.026656Z"
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Порядок проверки верный: победа обнаружена раньше ничьей.\n"
     ]
    }
   ],
   "source": [
    "# Поле полностью заполнено, И последний ход выигрывает диагональ 0-4-8\n",
    "poslednij_hod_pobeda = [\"X\", \"O\", \"O\",\n",
    "                        \"O\", \"X\", \"X\",\n",
    "                        \"O\", \"X\", \"X\"]\n",
    "\n",
    "winner, line = find_winner(poslednij_hod_pobeda)\n",
    "assert winner == \"X\"\n",
    "assert set(line) == {0, 4, 8}\n",
    "assert is_draw(poslednij_hod_pobeda) is False, \"победа на последнем ходу — это НЕ ничья\"\n",
    "print(\"Порядок проверки верный: победа обнаружена раньше ничьей.\")"
   ]
  }
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