CRT裸题......
我为了复习数论，用CRT和EXCRT分别把这道题写了一遍QAQ
CRT：
1 #include<cstdio> 2 #define ll long long 3 4 int n; 5 ll bp=1,ans; 6 ll aa[15],bb[15]; 7 8 void exgcd(ll a,ll b,ll &x,ll &y) 9 { 10 if(!b) 11 { 12 x=1,y=0; 13 return; 14 } 15 exgcd(b,a%b,y,x); 16 y-=a/b*x; 17 } 18 19 ll mul(ll a,ll b,ll mod) 20 { 21 ll ret=0; 22 while(b) 23 { 24 if(b&1)ret=(ret+a)%mod; 25 a=(a+a)%mod; 26 b>>=1; 27 } 28 return ret; 29 } 30 31 int main() 32 { 33 scanf("%d",&n); 34 for(int i=1;i<=n;i++)scanf("%lld",&aa[i]); 35 for(int i=1;i<=n;i++)scanf("%lld",&bb[i]),bp=bp*bb[i]; 36 for(int i=1;i<=n;i++) 37 { 38 aa[i]=(aa[i]%bb[i]+bb[i])%bb[i]; 39 ll bt=bp/bb[i]; 40 //bt*inv+bb[i]*k=1 41 ll inv,k; 42 exgcd(bt,bb[i],inv,k); 43 inv=(inv%bb[i]+bb[i])%bb[i]; 44 ans=(ans+mul(mul(bt,inv,bp),aa[i],bp))%bp; 45 } 46 printf("%lld",ans); 47 return 0; 48 }
EXCRT：
1 #include<cstdio> 2 #define ll long long 3 4 int n; 5 ll aa[15],bb[15]; 6 ll bp=1,ans; 7 8 ll exgcd(ll a,ll b,ll &x,ll &y) 9 { 10 if(!b) 11 { 12 x=1,y=0; 13 return a; 14 } 15 ll ret=exgcd(b,a%b,y,x); 16 y-=a/b*x; 17 return ret; 18 } 19 20 ll mul(ll a,ll b,ll mod) 21 { 22 ll ret=0; 23 while(b) 24 { 25 if(b&1)ret=(ret+a)%mod; 26 a=(a+a)%mod; 27 b>>=1; 28 } 29 return ret; 30 } 31 32 int main() 33 { 34 scanf("%d",&n); 35 for(int i=1;i<=n;i++)scanf("%lld",&aa[i]); 36 for(int i=1;i<=n;i++)scanf("%lld",&bb[i]); 37 for(int i=1;i<=n;i++) 38 { 39 ll c=((aa[i]-ans)%bb[i]+bb[i])%bb[i]; 40 ll k,kk; 41 ll g=exgcd(bp,bb[i],k,kk); 42 c/=g,bb[i]/=g; 43 k=mul(k,c,bb[i]); 44 ans=ans+k*bp; 45 bp=bp*bb[i]; 46 ans=(ans%bp+bp)%bp; 47 } 48 printf("%lld",ans); 49 return 0; 50 }