CPP Fastest and  2 line code solution
\nclass Solution {\npublic:\n    vector<int> getConcatenation(vector<int>& nums) {\n         \n\t\t // Arg1 - 1st vector end\n\t\t // Arg2 - 2nd vector start\n\
```\nclass Solution {\npublic:\n    vector<int> getConcatenation(vector<int>& nums) {\n         \n\t\t // Arg1 - 1st vector end\n\t\t // Arg2 - 2nd vector start\n\t\t // Arg3 - 2nd vector end\n        nums.insert(nums.end(), nums.begin(), nums.end());\n        \n        return nums;\n        \n    }\n};\n```\n\n# Please upvote if it is helpful to you, thank you.
['C']