LA 4270 离散平方根

#include<cstdio>#include<cstring>#include<algorithm>typedef long long LL;using namespace std;LL X,n,r;void exgcd(LL a,LL b,LL &d,LL &x,LL &y){if(b==0){d=a;x=1;y=0;}else{exgcd(b,a%b,d,y,x);y-=(a/b)*x;}}LL res[100000],cnt;void add(LL a,LL b){LL c=2*r,d,x,y,t;exgcd(a,b,d,x,y);if(c%d==0){x*=c/d,y*=c/d;t=a/d;for(int i=y%t;i*b-r<n;i+=t)if(i*b-r>=0&&(i*b-r)*(i*b-r)%n==X)    res[cnt++]=i*b-r;}}void solve(){cnt=1;res[0]=r;for(int i=1;i*i<=n;i++){if(n%i==0){add(i,n/i);    add(n/i,i);}}sort(res,res+cnt);cnt=unique(res,res+cnt)-res;for(int i=0;i<cnt;i++)printf(" %lld",res[i]);printf("\n");}int main(){int t=1;while(~scanf("%lld%lld%lld",&X,&n,&r)&&(n+X+r)){printf("Case %d:",t++);solve();}}