44 lines
1.1 KiB
C++
44 lines
1.1 KiB
C++
#include <iomanip>
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#include <iostream>
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#include <vector>
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std::vector<int> mertens_numbers(int max) {
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std::vector<int> m(max + 1, 1);
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for (int n = 2; n <= max; ++n) {
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for (int k = 2; k <= n; ++k)
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m[n] -= m[n / k];
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}
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return m;
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}
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int main() {
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const int max = 1000;
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auto m(mertens_numbers(max));
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std::cout << "First 199 Mertens numbers:\n";
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for (int i = 0, column = 0; i < 200; ++i) {
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if (column > 0)
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std::cout << ' ';
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if (i == 0)
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std::cout << " ";
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else
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std::cout << std::setw(2) << m[i];
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++column;
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if (column == 20) {
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std::cout << '\n';
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column = 0;
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}
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}
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int zero = 0, cross = 0, previous = 0;
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for (int i = 1; i <= max; ++i) {
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if (m[i] == 0) {
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++zero;
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if (previous != 0)
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++cross;
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}
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previous = m[i];
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}
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std::cout << "M(n) is zero " << zero << " times for 1 <= n <= 1000.\n";
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std::cout << "M(n) crosses zero " << cross << " times for 1 <= n <= 1000.\n";
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return 0;
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}
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