Mai intai trebuie sa te autentifici.
Cod sursa(job #3134757)
| Utilizator | Data | 30 mai 2023 19:12:24 | |
|---|---|---|---|
| Problema | Invers modular | Scor | 50 |
| Compilator | c-64 | Status | done |
| Runda | Arhiva educationala | Marime | 0.72 kb |
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
int phi(int n)
{
int result = n;
for (int i = 2; i * i <= n; i++)
{
if (n % i == 0)
{
while (n % i == 0)
n /= i;
result -= result / i;
}
}
if (n > 1)
result -= result / n;
return result;
}
FILE *file;
int main()
{
int a, n;
file = fopen("inversmodular.in", "r");
fscanf(file, "%d", &a);
fscanf(file, "%d", &n);
fclose(file);
int p = phi(n) - 1;
long long power, sol = 1;
// printf("phi %d\n", p);
power = a;
for (uint32_t i = 0; (1 << i) <= p; ++i)
{
if ((1 << i) & p)
sol = (sol * power) % n;
power = (power * power) % n;
}
file = fopen("inversmodular.out", "w");
fprintf(file, "%lld\n", sol % n);
fclose(file);
return 0;
}
