Hash Map Solution
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\npublic:\n    bool canFormArray(vector<int>& arr, vector<vector<int>>& pieces) {\n        unordered_map<int, vector<int>> mapPieces;\n        int index = 0, n = arr.size();\n        for (auto it : pieces) {\n            mapPieces[it[0]] = it;\n        }\n        while (index < n) {\n            if (mapPieces.find(arr[index]) == mapPieces.end()) {\n                return false;\n            }\n            auto piece = mapPieces[arr[index]];\n            for (int x : piece) {\n                if (x != arr[index]) {\n                    return false;\n                }\n                index++;\n            }\n        }\n        return true;\n    }\n};\n```
['C++']