xudyh的gcd模板

hdu 5019

 #include <cstdlib>
 #include <cctype>
 #include <cstring>
 #include <cstdio>
 #include <cmath>
 #include <algorithm>
 #include <vector>
 #include <string>
 #include <iostream>
 #include <map>
 #include <set>
 #include <queue>
 #include <stack>
 #include <bitset>
 #include <list>
 #include <cassert>
 #include <complex>
 using namespace std;
 #define rep(i,a,n) for (int i=a;i<n;i++)
 #define per(i,a,n) for (int i=n-1;i>=a;i--)
 #define all(x) (x).begin(),(x).end()
 //#define fi first
 #define se second
 #define SZ(x) ((int)(x).size())
 #define TWO(x) (1<<(x))
 #define TWOL(x) (1ll<<(x))
 #define clr(a) memset(a,0,sizeof(a))
 #define POSIN(x,y) (0<=(x)&&(x)<n&&0<=(y)&&(y)<m)
 typedef vector<int> VI;
 typedef vector<string> VS;
 typedef vector<double> VD;
 typedef long long ll;
 typedef long double LD;
 typedef pair<int,int> PII;
 typedef pair<ll,ll> PLL;
 typedef vector<ll> VL;
 typedef vector<PII> VPII;
 typedef complex<double> CD;
 const int inf=0x20202020;
 const ll mod=;
 const double eps=1e-;

 ll powmod(ll a,ll b)             //return (a*b)%mod
 {ll res=;a%=mod;for(;b;b>>=){if(b&)res=res*a%mod;a=a*a%mod;}return res;}
 ll powmod(ll a,ll b,ll mod)     //return (a*b)%mod
 {ll res=;a%=mod;for(;b;b>>=){if(b&)res=res*a%mod;a=a*a%mod;}return res;}
 ll gcd(ll a,ll b)                 //return gcd(a,b)
 { return b?gcd(b,a%b):a;}
 // head

 namespace Factor {
     const int N=;
     ll C,fac[],n,mut,a[];
     int T,cnt,i,l,prime[N],p[N],psize,_cnt;
     ll _e[],_pr[];
     vector<ll> d;

     inline ll mul(ll a,ll b,ll p) {     //return (a*b)%p
         if (p<=) return a*b%p;
         else if (p<=1000000000000ll) return (((a*(b>>)%p)<<)+(a*(b&((<<)-))))%p;
         else {
             ll d=(ll)floor(a*(long double)b/p+0.5);
             ll ret=(a*b-d*p)%p;
             if (ret<) ret+=p;
             return ret;
         }
     }

     void prime_table(){     //prime[1..tot]: prime[i]=ith prime
         int i,j,tot,t1;
         for (i=;i<=psize;i++) p[i]=i;
         for (i=,tot=;i<=psize;i++){
             if (p[i]==i) prime[++tot]=i;
             for (j=;j<=tot && (t1=prime[j]*i)<=psize;j++){
                 p[t1]=prime[j];
                 if (i%prime[j]==) break;
             }
         }
     }

     void init(int ps) {                 //initial
         psize=ps;
         prime_table();
     }

     ll powl(ll a,ll n,ll p) {           //return (a^n)%p
         ll ans=;
         for (;n;n>>=) {
             if (n&) ans=mul(ans,a,p);
             a=mul(a,a,p);
         }
         return ans;
     }

     bool witness(ll a,ll n) {
         int t=;
         ll u=n-;
         for (;~u&;u>>=) t++;
         ll x=powl(a,u,n),_x=;
         for (;t;t--) {
             _x=mul(x,x,n);
             if (_x== && x!= && x!=n-) return ;
             x=_x;
         }
         return _x!=;
     }

     bool miller(ll n) {
         if (n<) return ;
         if (n<=psize) return p[n]==n;
         if (~n&) return ;
         for (int j=;j<=;j++) if (witness(rand()%(n-)+,n)) return ;
         return ;
     }

     ll gcd(ll a,ll b) {
         ll ret=;
         while (a!=) {
             if ((~a&) && (~b&)) ret<<=,a>>=,b>>=;
             else if (~a&) a>>=; else if (~b&) b>>=;
             else {
                 if (a<b) swap(a,b);
                 a-=b;
             }
         }
         return ret*b;
     }

     ll rho(ll n) {
         for (;;) {
             ll X=rand()%n,Y,Z,T=,*lY=a,*lX=lY;
             int tmp=;
             C=rand()%+;
             X=mul(X,X,n)+C;*(lY++)=X;lX++;
             Y=mul(X,X,n)+C;*(lY++)=Y;
             for(;X!=Y;) {
                 ll t=X-Y+n;
                 Z=mul(T,t,n);
                 if(Z==) return gcd(T,n);
                 tmp--;
                 if (tmp==) {
                     tmp=;
                     Z=gcd(Z,n);
                     if (Z!= && Z!=n) return Z;
                 }
                 T=Z;
                 Y=*(lY++)=mul(Y,Y,n)+C;
                 Y=*(lY++)=mul(Y,Y,n)+C;
                 X=*(lX++);
             }
         }
     }

     void _factor(ll n) {
         for (int i=;i<cnt;i++) {
             if (n%fac[i]==) n/=fac[i],fac[cnt++]=fac[i];}
         if (n<=psize) {
             for (;n!=;n/=p[n]) fac[cnt++]=p[n];
             return;
         }
         if (miller(n)) fac[cnt++]=n;
         else {
             ll x=rho(n);
             _factor(x);_factor(n/x);
         }
     }

     void dfs(ll x,int dep) {
         if (dep==_cnt) d.push_back(x);
         else {
             dfs(x,dep+);
             for (int i=;i<=_e[dep];i++) dfs(x*=_pr[dep],dep+);
         }
     }

     void norm() {
         sort(fac,fac+cnt);
         _cnt=;
         rep(i,,cnt) if (i==||fac[i]!=fac[i-]) _pr[_cnt]=fac[i],_e[_cnt++]=;
             else _e[_cnt-]++;
     }

     vector<ll> getd() {
         d.clear();
         dfs(,);
         return d;
     }

     vector<ll> factor(ll n) {       //return all factors of n        cnt:the number of factors
         cnt=;
         _factor(n);
         norm();
         return getd();
     }

     vector<PLL> factorG(ll n) {
         cnt=;
         _factor(n);
         norm();
         vector<PLL> d;
         rep(i,,_cnt) d.push_back(make_pair(_pr[i],_e[i]));
         return d;
     }

     bool is_primitive(ll a,ll p) {
         //assert(miller(p));
         vector<PLL> D=factorG(p-);
         rep(i,,SZ(D)) if (powmod(a,(p-)/D[i].first,p)==) return ;
         return ;
     }
 }

 ll x,y,k;
 int _;
 int main() {
     Factor::init();
     for (scanf("%d",&_);_;_--) {
         scanf("%I64d%I64d%I64d",&x,&y,&k);
         vector<ll> c=Factor::factor(gcd(x,y));      //c:all factors of gcd(x,y)
         sort(all(c));                               // =all common factors of x and y
         reverse(all(c));
         if (SZ(c)<k) puts("-1"); else printf("%I64d\n",c[k-]);
     }
 }