Cod sursa(job #2756680)
Utilizator | Matei Balaur12 matei.balaur2009 | Data | 2 iunie 2021 12:13:05 |
---|---|---|---|
Problema | Invers modular | Scor | 70 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.74 kb |
#include <fstream>
using namespace std;
ifstream in("inversmodular.in");
ofstream out("inversmodular.out");
int a,n;
int euler(int x) {
int e=1;
if(x%2==0) {
x/=2;
while(x%2==0) {
x/=2;
e*=2;
}
}
for(int d=3; d*d<=x; d+=3)
if(x%d==0) {
x/=d;
e*=d-1;
while(x%d==0) {
x/=d;
e*=d;
}
}
if(x>1)
e*=x-1;
return e;
}
int putere(int b,int e) {
if(e==0)
return 1;
int r=putere(b,e/2);
r=1LL*r*r%n;
if(e%2==1)
r=1LL*r*b%n;
return r;
}
int main() {
in>>a>>n;
out<<putere(a,euler(n)-1);
return 0;
}