Hdu4992 primitive roots (all original roots)

Question link: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 4992

Question: Give N and output all the original roots of N.

Idea: obtain an original root X of N. For the I, I <PHI (n) and (I, Phi (N) = 1, x ^ I % N is the original root of N.

 

int Euler(int n){    int i,ans=n;    for(i=2;i*i<=n;i++) if(n%i==0)    {        ans=ans/i*(i-1);        while(n%i==0) n/=i;    }    if(n>1) ans=ans/n*(n-1);    return ans;}int prime[N],tag[N],cnt;void init(){int i,j;for(i=2;i<N;i++) if(!tag[i]){prime[cnt++]=i;for(j=i+i;j<N;j+=i) tag[j]=1;}tag[1]=1;}int get(int x){if(x%2==0) return 0;int i;for(i=0;i<cnt&&prime[i]*prime[i]<=x;i++) if(x%prime[i]==0){while(x%prime[i]==0) x/=prime[i];if(x!=1) return 0;return prime[i];}return x;}int n;int myPow(i64 x,i64 y){i64 ans=1;while(y){if(y&1) ans=ans*x%n;x=x*x%n;y>>=1;}return (int)ans;}int ee;vector<int> V;int ok(int t){if(myPow(t,ee)!=1) return 0;int i;FOR0(i,SZ(V)) if(myPow(t,V[i])==1) return 0;return 1;}int Gcd(int x,int y){if(y==0) return x;return Gcd(y,x%y);}int main(){init();while(scanf("%d",&n)!=-1){if(n==2){puts("1");continue;}if(n==4){puts("3");continue;}int t=n%2==0?get(n/2):get(n);if(!t){puts("-1");continue;}ee=Euler(n);V.clear();int i;for(i=2;i*i<=ee;i++) if(ee%i==0){V.pb(i);if(i*i!=ee) V.pb(ee/i);}for(i=2;i<n;i++) if(ok(i)) break;int Min=i;vector<int> ans;for(i=1;i<ee;i++) {if(Gcd(i,ee)!=1) continue;ans.pb(myPow(Min,i));}sort(all(ans));for(i=0;i<SZ(ans);i++){if(i) putchar(‘ ‘);printf("%d",ans[i]);}puts("");}}

 

Hdu4992 primitive roots (all original roots)