中国剩余定理(excrt) 模板

excrt板子题

 #include <cmath>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #define ll long long
 #define N 100010
 #define rint register int
 #define ll long long
 #define il inline
 using namespace std;
 //re
 int n;
 ll A[N],B[N];
 ll qadd(ll x,ll y,const ll &mo){ll ans=;while(y){if(y&)ans=(ans+x)%mo;x=(x+x)%mo;y>>=;}return ans;}
 ll qpow(ll x,ll y,const ll &mo){ll ans=;while(y){if(y&)ans=(ans*x)%mo;x=(x*x)%mo;y>>=;}return ans;}
 ll exgcd(ll a,ll b,ll &x,ll &y){
     if(b==){x=,y=;return a;}
     ll ans=exgcd(b,a%b,x,y);
     ll t=x;x=y;y=t-a/b*y;
     return ans;
 }
 ll excrt()
 {
     ll x,y,ans=A[],M=B[],bg;
     for(int i=;i<=n;i++)
     {
         ll a=M,b=B[i],c=(A[i]-ans%b+b)%b;
         ll gcd=exgcd(M,b,x,y);bg=b/gcd;
         if(c%gcd!=) return -;
         x=qadd(x,c/gcd,bg);
         ans+=x*M;
         M*=bg;
         ans=(ans%M+M)%M;
     }
     return ans;
 }

 int main()
 {
     scanf("%d",&n);
     for(int i=;i<=n;i++)
         scanf("%lld%lld",&B[i],&A[i]);
     printf("%lld\n",excrt());
     return ;
 }