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      "True\n",
      "False\n",
      "True\n"
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   "source": [
    "# ---------------------------------------------------------------\n",
    "# python best courses https://courses.tanpham.org/\n",
    "# ---------------------------------------------------------------\n",
    "# Write a Python program to find validity of a string of parentheses, '(', ')', '{', '}', '[' and ']. \n",
    "# These brackets must be close in the correct order, \n",
    "# for example \"()\" and \"()[]{}\" are valid but \"[)\", \"({[)]\" and \"{{{\" are invalid.\n",
    "\n",
    "class py_solution:\n",
    "   def is_valid_parenthese(self, str1):\n",
    "        stack, pchar = [], {\"(\": \")\", \"{\": \"}\", \"[\": \"]\"}\n",
    "        for parenthese in str1:\n",
    "            if parenthese in pchar:\n",
    "                stack.append(parenthese)\n",
    "            elif len(stack) == 0 or pchar[stack.pop()] != parenthese:\n",
    "                return False\n",
    "        return len(stack) == 0\n",
    "\n",
    "print(py_solution().is_valid_parenthese(\"(){}[]\"))\n",
    "print(py_solution().is_valid_parenthese(\"()[{)}\"))\n",
    "print(py_solution().is_valid_parenthese(\"()\"))"
   ]
  }
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