`
java-mans
  • 浏览: 11339314 次
文章分类
社区版块
存档分类
最新评论

pku1284 Primitive Roots

 
阅读更多
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;

#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\n"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\n"
#define in64 "%lld"
#endif
/************ for topcoder by zz1215 *******************/
#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FFF(i,a)        for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a,b)      for( int i = (a) ; i >= (b) ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf = 0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-9;
const double pi = acos(-1.0);

// i64 gcd(i64 a,i64 b){return b?gcd(b,a%b):a;}

i64 gcd(i64 _a, i64 _b)
{
    if (!_a || !_b)
    {
        return max(_a, _b);
    }
    i64 _t;
    while ((_t = _a % _b))
    {
        _a = _b;
        _b = _t;
    }
    return _b;
}

i64 ext_gcd (i64 _a, i64 _b, i64 &_x, i64 &_y)
{
    if (!_b)
    {
        _x = 1;
        _y = 0;

        return _a;
    }
    i64 _d = ext_gcd (_b, _a % _b, _x, _y);
    i64 _t = _x;
    _x = _y;
    _y = _t - _a / _b * _y;
    return _d;
}

i64 invmod (i64 _a, i64 _p)
{
    i64 _ans, _y;
    ext_gcd (_a, _p, _ans, _y);
    _ans < 0 ? _ans += _p : 0;
    return _ans;
}

const int maxn = 10000;

vector<int>p;
int n;

bool isp(int x)
{
    int temp = sqrt(double(x));
    for(int i=0;i<p.size();i++)
    {
        if(p[i] > temp)
        {
            return true;
        }
        if(!(x%p[i]))
        {
            return false;
        }
    }
    return true;
}

void init()
{
    p.clear();
    p.pb(2);
    for(int i=3;i<maxn;i++)
    {
        if(isp(i))
        {
            p.pb(i);
        }
    }
    return ;
}

int phi(int x)
{
    int ans = 1;
    int temp;
    int num;
    for(int i=0;p[i]*p[i]<=x;i++)
    {
        temp = 0;
        while(x%p[i]==0)
        {
            x/=p[i];
            if(!temp)
            {
                temp = p[i]-1;
            }
            else
            {
                temp *= p[i];
            }
        }
        if(temp)
        {
            ans*=temp;
        }
    }
    if(x!=1)
    {
        ans*=x-1;
    }
    return ans;
}

int main()
{
    init();
    while(cin>>n)
    {
        cout<<phi(n-1)<<endl;
    }
    return 0;
}


分享到:
评论

相关推荐

Global site tag (gtag.js) - Google Analytics