C++ / Python (1 line) simple solution
C++ :\n\n\nvector<int> getConcatenation(vector<int>& nums) {\n\tint size = nums.size();\n\n\tfor(int i = 0; i < size; ++i)\n\t\tnums.push_back(nums[i]);\n\n\tre
**C++ :**\n\n```\nvector<int> getConcatenation(vector<int>& nums) {\n\tint size = nums.size();\n\n\tfor(int i = 0; i < size; ++i)\n\t\tnums.push_back(nums[i]);\n\n\treturn nums;\n}\n```\n\n**Python :**\n\n```\ndef getConcatenation(self, nums: List[int]) -> List[int]:\n\treturn nums * 2\n```\n\n**Like it  ? please upvote !**
['C', 'Python', 'C++', 'Python3']