math/miller_rabin.cpp

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• Last update: 2021-03-26 19:37:21+09:00

Verified with

• test/yuki3030.test.cpp

Code

template< class T>
T pow_ (T x, uint64_t n, uint64_t M){
    T u = 1;
    if(n > 0){
        u = pow_(x, n/2, M);
        if (n % 2 == 0) u = (u*u) % M;
        else u = (((u * u)% M) * x) % M;
    }
    return u;
};

bool suspect(__uint128_t a, uint64_t s, uint64_t d, uint64_t n){
    __uint128_t x = pow_(a, d, n);
    if (x == 1) return true;
    for (int r = 0; r < s; ++r) {
        if(x == n-1) return true;
        x = x * x % n;
    }
    return false;
}

template<class T>
bool miller_rabin(T m){
    uint64_t n = m;
    if (n <= 1 || (n > 2 && n % 2 == 0)) return false;
    uint64_t d = n - 1, s = 0;
    while (!(d&1)) {++s; d >>= 1;}
    vector<uint64_t> v = {2, 325, 9375, 28178, 450775, 9780504, 1795265022};
    if(n < 4759123141LL) v = {2, 7, 61};
    for (auto &&p : v) {
        if(p >= n) break;
        if(!suspect(p, s, d, n)) return false;
    }
    return true;
}

#line 1 "math/miller_rabin.cpp"
template< class T>
T pow_ (T x, uint64_t n, uint64_t M){
    T u = 1;
    if(n > 0){
        u = pow_(x, n/2, M);
        if (n % 2 == 0) u = (u*u) % M;
        else u = (((u * u)% M) * x) % M;
    }
    return u;
};

bool suspect(__uint128_t a, uint64_t s, uint64_t d, uint64_t n){
    __uint128_t x = pow_(a, d, n);
    if (x == 1) return true;
    for (int r = 0; r < s; ++r) {
        if(x == n-1) return true;
        x = x * x % n;
    }
    return false;
}

template<class T>
bool miller_rabin(T m){
    uint64_t n = m;
    if (n <= 1 || (n > 2 && n % 2 == 0)) return false;
    uint64_t d = n - 1, s = 0;
    while (!(d&1)) {++s; d >>= 1;}
    vector<uint64_t> v = {2, 325, 9375, 28178, 450775, 9780504, 1795265022};
    if(n < 4759123141LL) v = {2, 7, 61};
    for (auto &&p : v) {
        if(p >= n) break;
        if(!suspect(p, s, d, n)) return false;
    }
    return true;
}

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