Math problem, Arithmetic sequence O(1)
\npublic class Solution {\n    public int MinOperations(int n) {\n        int len = n / 2;\n        int min = n % 2 == 0 ? 1 : 2;\n\t\tint max = min + (len - 1)
```\npublic class Solution {\n    public int MinOperations(int n) {\n        int len = n / 2;\n        int min = n % 2 == 0 ? 1 : 2;\n\t\tint max = min + (len - 1) * 2;\n        return (min + max) * len / 2;\n    }\n}\n```
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