excrt板子题
1 #include <cmath> 2 #include <cstdio> 3 #include <cstring> 4 #include <algorithm> 5 #define ll long long 6 #define N 100010 7 #define rint register int 8 #define ll long long 9 #define il inline 10 using namespace std; 11 //re 12 int n; 13 ll A[N],B[N]; 14 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;} 15 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;} 16 ll exgcd(ll a,ll b,ll &x,ll &y){ 17 if(b==0){x=1,y=0;return a;} 18 ll ans=exgcd(b,a%b,x,y); 19 ll t=x;x=y;y=t-a/b*y; 20 return ans; 21 } 22 ll excrt() 23 { 24 ll x,y,ans=A[1],M=B[1],bg; 25 for(int i=2;i<=n;i++) 26 { 27 ll a=M,b=B[i],c=(A[i]-ans%b+b)%b; 28 ll gcd=exgcd(M,b,x,y);bg=b/gcd; 29 if(c%gcd!=0) return -1; 30 x=qadd(x,c/gcd,bg); 31 ans+=x*M; 32 M*=bg; 33 ans=(ans%M+M)%M; 34 } 35 return ans; 36 } 37 38 int main() 39 { 40 scanf("%d",&n); 41 for(int i=1;i<=n;i++) 42 scanf("%lld%lld",&B[i],&A[i]); 43 printf("%lld ",excrt()); 44 return 0; 45 }