25 lines
454 B
C++
25 lines
454 B
C++
#include <bits/stdc++.h>
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using namespace std;
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/**
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* 功能：欧拉函数
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* @param x
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* @return
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*/
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int phi(int x) {
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int res = x;
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for (int i = 2; i <= x / i; i++)
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if (x % i == 0) {
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res = res / i * (i - 1);
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while (x % i == 0) x /= i;
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}
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if (x > 1) res = res / x * (x - 1);
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return res;
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}
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int main() {
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cout << phi(2) << endl;
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cout << phi(8) << endl;
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return 0;
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} |