Hdu 1573 线性同余方程组

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#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>#include <cstdlib>#include <cmath>#include <queue>#include <vector>#include <map>#define pb push_back#define mp make_pair#define eps 1e-9#define zero(x) (fabs(x)<eps)#define pi acos(-1.0)#define f1 first#define f2 second#define lson l,mid,rt<<1#define rson mid+1,r,rt<<1|1#define initial 1,n,1const int inf=0x3f3f3f3f;const long long INF=1LL<<50;using namespace std;typedef long long LL;typedef pair <int, int> PII;template<typename X> inline bool minimize(X&p,X q){if(p<=q)return 0;p=q;return 1;}template<typename X> inline bool maximize(X&p,X q){if(p>=q)return 0;p=q;return 1;}#define N 15int a[N],b[N],c[N];int n,rr;int exgcd(int a,int b,int &x,int &y){    int d=a;    if (b)        {            d=exgcd(b,a%b,y,x);            y-=a/b*x;        }    else{   x=1;y=0;}    return d;}int mod_inverse(int a,int m){    int x,y;    exgcd(a,m,x,y);    return (m+x%m)%m;}int gcd(int a,int b){    if (a%b==0) return b;    return gcd(b,a%b);}PII lin(int *aa,int *bb,int *cc,int nn){    int x=0,m=1;    for (int i=0;i<nn;i++)        {            int a=aa[i]*m,b=bb[i]-aa[i]*x,d=gcd(cc[i],a);            if (b%d!=0) return mp(0,-1);            int t=b/d*mod_inverse(a/d,cc[i]/d)%(cc[i]/d);            x=x+m*t;            m*=cc[i]/d;        }    return mp((x%m+m)%m,m);}void doit(){   scanf("%d%d",&rr,&n);    for (int i=0;i<n;i++)scanf("%d",&c[i]);    for (int i=0;i<n;i++)scanf("%d",&b[i]);    for (int i=0;i<n;i++)a[i]=1;    PII re=lin(a,b,c,n);    if (re.f2==-1) printf("%d\n",0);else    printf("%d\n",(rr+re.f2-re.f1)/re.f2-(re.f2-re.f1)/re.f2);}int main(){    int cas;    scanf("%d",&cas);    while (cas--) doit();}

PII china(int *bb,int *cc,int nn){   int t=1,ans=0;    for (int i=0;i<nn;i++)        t=t*cc[i];    for (int i=0;i<nn;i++)        {   int x,y;            exgcd(t/cc[i],cc[i],x,y);x+=cc[i];            ans+=t/cc[i]*x*b[i];            ans%=t;        }    return mp((ans+t)%t,t);}

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