hdu 3579 Hello Kiki

題目地址：http://acm.hdu.edu.cn/showproblem.php?pid=3579

要點; 題目要求正整數，一旦r1=0;應該輸出最小公倍數

#include<iostream>#include<cstdio>using namespace std;typedef long long inta;void extend_gcd(inta a,inta b,inta &x,inta &y,inta &gcd){    if(b==0)    {       x=1;       y=0;       gcd=a;    }    else    {      extend_gcd(b,a%b,x,y,gcd);      inta temp=x;      x=y;      y=temp-a/b*y;    }}int main(){   int size=0;   cin>>size;   for(int i=0;i<size;i++) {    int n;    cin>>n;    int *a=new int[n];    int *r=new int[n];     for(int i=0;i<n;i++)        cin>>a[i];     for(int i=0;i<n;i++)        cin>>r[i];   inta a1,r1,a2,r2,x,y;    a1=a[0];    r1=r[0];    int bad=0;   for(int i=1;i<n;i++)    {       a2=a[i];       r2=r[i];       inta a=a1;       inta b=a2;       inta c=r2-r1;       inta q=1;       extend_gcd(a,b,x,y,q);       if(c%q!=0)       {          bad=1;       }       else       {          inta t=b/q;          x=(c/q*x%t+t)%t;          r1=a1*x+r1;          a1=a1/q*a2;          r1=r1%a1;       }    }     cout<<"Case "<<i+1<<": ";      if(bad==0)      {      if(r1>0)      cout<<r1<<endl;      else      cout<<a1<<endl;      }      else cout<<-1<<endl;   }}