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https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
32 lines
689 B
C++
32 lines
689 B
C++
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#include<cstdio>
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#include<cmath>
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#include<cstring>
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#include<queue>
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#include<vector>
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#include<ctime>
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#include<functional>
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#include<algorithm>
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using namespace std;
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typedef long long LL;
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typedef pair<int, int> PII;
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const int MX = 1e3 + 5;
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const int INF = 0x3f3f3f3f;
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const int mod = 1e9 + 7;
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LL eular(LL n) {
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LL ans = n;
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for(int i = 2; (LL)i * i <= n; i++) {
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if(n % i == 0) {
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ans -= ans / i;
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while(n % i == 0) n /= i;
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}
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}
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if(n > 1) ans -= ans / n;
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return ans;
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}
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int main() {
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LL n;
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while(~scanf("%I64dd", &n), n) {
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printf("%I64d\n", (n * (n - 1) / 2 - eular(n) * n / 2) % mod);
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}
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}
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