hdu 4135 Co-prime(容斥原理)

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#include <bits/stdc++.h>using namespace std;typedef long long LL;LL solve(LL num, LL n){    vector<LL> p;    LL temp = n;    for(LL i = 2; i <= temp/i; ++i)    {        if(temp%i == 0)        {            p.push_back(i);            while(temp%i == 0) temp /= i;        }    }    if(temp > 1) p.push_back(temp);    LL res = 0;    for(int i = 1; i < (1<<p.size()); ++i)    {        LL mult = 1;        int cnt = 0;        for(int j = 0; j < p.size(); ++j)        {            if(i&(1<<j))            {                mult *= p[j];                ++cnt;            }        }        if(cnt&1) res += num/mult;        else res -= num/mult;    }    return num-res;}int main(){    ios::sync_with_stdio(false);    int T;    LL A,B,N;    int time = 0;    cin >> T;    while(T--)    {        cin >> A >> B >> N;        cout << "Case #" << ++time << ": ";        cout << solve(B,N)-solve(A-1,N) << endl;    }    return 0;}

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