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  • HDU 4344 随机法判素数(费马小定理

    #include <cstdio>
    #include <ctime>
    #include <cmath>
    #include <algorithm>
    using namespace std;
    typedef long long ll;
    const int N = 108;
    const int S = 10;
    
    ll mult_mod(ll a, ll b, ll c) {
        a %= c;
        b %= c;
        ll ret = 0;
        while(b) {
            if(b&1) ret = (ret + a) % c;
            a = (a + a) % c;
            b >>= 1;
        }
        return ret;
    }
    ll pow_mod(ll x, ll n, ll mod) {
        if(n == 1) return x % mod;
        x %= mod;
        ll tmp = x, ret = 1;
        while(n > 0){
            if(n&1) ret = mult_mod(ret, tmp, mod);
            tmp = mult_mod(tmp, tmp, mod);
            n >>= 1;
        }
        return ret;
    }
    
    bool check(ll a, ll n, ll x, ll t) {
        ll ret = pow_mod(a, x, n);
        ll last = ret;
        for(int i = 1; i <= t; i ++) {
            ret = mult_mod(ret, ret, n);
            if(ret == 1 && last != 1 && last != n-1) return true;
            last = ret;
        }
        if(ret != 1) return true;
        return false;
        
    }
    bool Miller_Rabin(ll n) {
        if(n < 2) return false;
        if(n==2||n==3||n==5||n==7) return true;
        if(n%2==0||n%3==0||n%5==0||n%7==0) return false;
        
        ll x = n - 1, t = 0;
        while((x&1)==0) {
            x >>= 1;
            t ++;
        }
        for(int i = 0; i < S; i ++) {
            ll a = rand()%(n-1) +1;
            if(check(a, n, x, t)) return false;
        }
        return true;
    }
    ll gcd(ll a, ll b) {
        if(a < 0) return gcd(-a, b);
        if(b < 0) return gcd(a, -b);
        while(a > 0 && b > 0) {
            if(a > b) a %= b;
            else b %= a;
        }
        return a+b;
    }
    ll Pollard_rho(ll x, ll c) {
        ll i = 1, k = 2;
        ll x0 = ((rand() % x) + x) % x;
        ll y = x0;
        while(true) {
            i ++;
            x0 = (mult_mod(x0, x0, x) + c)%x;
            ll d = gcd(y-x0, x);
            if(d != 1 && d != x) return d;
            if(y == x0) return x;
            if(i == k) {
                y = x0;
                k += k;
            }
        }
        
    }
    ll P[N], tot;
    
    void findfac(ll n) {
        if(Miller_Rabin(n)) {
            P[tot++] = n;
            return ;
        }
        ll p = n;
        while(p >= n){
            p = Pollard_rho(p, rand()%(n-1)+1);
        }
        findfac(p);
        findfac(n/p);
    
    }
    int main() {
        int T;scanf("%d", &T);
        while(T-- > 0) {
            ll n;scanf("%I64d", &n);
            
            tot = 0;
            findfac(n);
            sort(P, P + tot);
            ll t = 0, ans = 0;
            for(int i = 0; i < tot; i ++) {
                if(!i || P[i] != P[i-1]) {
                    ans += pow_mod(P[i], count(P, P+tot, P[i]), n);
                    t ++;
                }
            }
            printf("%I64d %I64d
    ", t, t==1?n/P[0]:ans);
        }
        return 0;
    }

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  • 原文地址:https://www.cnblogs.com/zfyouxi/p/4199211.html
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