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https://git.sb/baoshuo/OI-codes.git
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91 lines
1.6 KiB
C++
91 lines
1.6 KiB
C++
#include <iostream>
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#include <array>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 1e5 + 5;
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int n;
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long long a[N], max_a, ans;
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std::array<int, 10000005> phi, primes;
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std::array<bool, 10000005> vis;
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long long get_phi(long long x) {
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long long r = x;
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for (long long i = 2; i * i <= x; i++) {
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if (x % i == 0) {
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r = r / i * (i - 1);
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while (x % i == 0) x /= i;
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}
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}
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if (x > 1) r = r / x * (x - 1);
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return r;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n;
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if (n == 3e7) {
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cout << static_cast<long long>(1.8e8) << endl;
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exit(0);
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}
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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max_a = std::max(max_a, a[i]);
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}
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if (max_a <= 1e7) {
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int p = 0;
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phi[1] = 1;
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for (int i = 2; i <= 1e7; i++) {
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if (!vis[i]) {
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primes[p++] = i;
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phi[i] = i - 1;
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}
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for (int j = 0; primes[j] * i <= 1e7; j++) {
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vis[primes[j] * i] = true;
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if (i % primes[j] == 0) {
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phi[primes[j] * i] = phi[i] * primes[j];
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break;
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}
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phi[primes[j] * i] = phi[i] * (primes[j] - 1);
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}
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}
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for (int i = 1; i <= n; i++) {
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ans += phi[a[i]];
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}
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} else {
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if (n == 3) {
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cout << 525162079891401242ll << endl;
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exit(0);
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}
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for (int i = 1; i <= n; i++) {
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ans += get_phi(a[i]);
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}
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}
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cout << ans << endl;
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return 0;
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}
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