中國剩餘定理(excrt) 模板

excrt板子題

#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=0;while(y){if(y&1)ans=(ans+x)%mo;x=(x+x)%mo;y>>=1;}return ans;}
ll qpow(ll x,ll y,const ll &mo){ll ans=1;while(y){if(y&1)ans=(ans*x)%mo;x=(x*x)%mo;y>>=1;}return ans;}
ll exgcd(ll a,ll b,ll &x,ll &y){
    if(b==0){x=1,y=0;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[1],M=B[1],bg;
    for(int i=2;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!=0) return -1;
        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=1;i<=n;i++)
        scanf("%lld%lld",&B[i],&A[i]);
    printf("%lld\n",excrt());
    return 0;
}