27 lines
525 B
C++
27 lines
525 B
C++
/*
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* 本来想打表的，打着打着发现了一些数学规律。具体怎么证明嘛……🤷
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*/
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#include <iostream>
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#include <cmath>
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constexpr size_t MAX_N = 10001;
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int get_ans(int n) {
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const int k = ceil(-0.5 + 0.5 * sqrt(4 * n + 1));
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const bool extra = k * k < n;
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const int ans = k * (k - 1) + 1 + k * extra;
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return ans;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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std::cin.tie(nullptr);
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int n;
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std::cin >> n;
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std::cout << get_ans(n) << std::endl;
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return 0;
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}
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