4000 hdu1573 X问题 一元模线性方程组

/*
题目描述：给出含m（1<= m <= 10）个形如x=bi (mod ai)的模线性方程组，问该方程组小于等于(1 <= n <= 1e9)
的解有多少个？

方法：正常解一元模线性方程组，自上向下合并，直至仅剩一个方程x = r (mod lcm(a1 ,a2 ,...,am))，若r > n 无解；
否则令r+lcm*x <= n，解出x，若r不等于0则x++，x即为答案
*/
#pragma warning(disable:4786)
#pragma comment(linker, "/STACK:102400000,102400000")
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<vector>
#include<cmath>
#include<string>
#include<sstream>
#define LL long long
#define FOR(i,f_start,f_end) for(int i=f_start;i<=f_end;++i)
#define mem(a,x) memset(a,x,sizeof(a))
#define lson l,m,x<<1
#define rson m+1,r,x<<1|1
using namespace std;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const double PI = acos(-1.0);
const double eps=1e-8;
LL a[15], b[15];
LL n , m;
LL ex_gcd(LL a , LL b , LL &x ,LL &y)
{
if(b==0){
x = 1 ;     y = 0;
return a;
}
LL d = ex_gcd(b , a%b , y , x);
y = y - a / b * x;
return d;
}
LL solve()
{
LL a1 , r1 , a2 , r2 , x0 , y0;
bool ok = 1;
a1 = a[1];      r1 = b[1];
for(int i = 2 ; i <= m ; i++){
a2 = a[i] ;     r2 = b[i];
LL d = ex_gcd(a1 , a2 , x0 , y0);
LL c = r2 - r1;
if(c % d){
ok = 0;
}
LL m= a2 / d;
x0 = (x0 * c / d % m + m)%m;
r1 = a1 * x0 + r1;
a1 = a1 * (a2 / d);
}
if(!ok)     return -1;
else{
if(n < r1)      return -1;
LL ret = (n - r1 ) / a1 ;
if(r1 !=0)      ++ret ;
return ret;
}
}
int main()
{
int T  ;
scanf("%d",&T);
while(T--){
scanf("%lld%lld",&n,&m);
FOR(i , 1 , m)  scanf("%lld",&a[i]);
FOR(i , 1 , m)  scanf("%lld",&b[i]);
LL ans = solve();
if(ans != -1)
printf("%lld\n",ans);
else
printf("0\n");
}
return 0;
}