int MainWindow::modInverse(int a, int m)
{
int x, y;
int res = 0;
int gcd = gcdExtended(a, m, &x, &y);
if (gcd == 1)
res = (x%m + m) % m;
return res;
}
//modular inverse works like GCD, but returns different value
long ModInverse(long a, long m){
int x, y;
long g = gcdExtended(a, m, &x, &y);
if (g != 1)
printf( "Inverse doesn't exist\n");
else{
// m is added to handle negative x
long res = (x%m + m) % m;
return res;
}
return -1;
}
int algebra::gcdExtended(int a, int b, int &x, int &y)
{
if(a == 0)
{
x = 0; y = 1;
return b;
}
int x1, y1;
int d = gcdExtended(b%a, a, x1, y1);
x = y1 - (b / a) * x1;
y = x1;
return d;
}
int MainWindow::gcdExtended(int a, int b, int *x, int *y)
{
if (a == 0)
{
*x = 0, *y = 1;
return b;
}
int x1, y1;
int gcd = gcdExtended(b%a, a, &x1, &y1);
*x = y1 - (b/a) * x1;
*y = x1;
return gcd;
}
//function for extended Euclidean Algorithm
int gcdExtended(int a, int b, int *x, int *y){
// Base Case
if (a == 0)
{
*x = 0, *y = 1;
return b;
}
int x1, y1; // To store results of recursive call
int gcd = gcdExtended(b%a, a, &x1, &y1);
// Update x and y using results of recursive
// call
*x = y1 - (b/a) * x1;
*y = x1;
return gcd;
}
