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*
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import java.util.Random;
/**
* An object that implements a cheesy pseudorandom permutation of the integers
* from zero to some user - specified value . ( The permutation is a linear
* function . )
*
* @ author Josh Bloch
*/
class Permuter {
/**
* The size of the permutation .
*/
private int modulus;
/**
* Nonnegative integer less than n that is relatively prime to m .
*/
private int multiplier;
/**
* Pseudorandom nonnegative integer less than n .
*/
private int addend = 22 ;
public Permuter(int n) {
if (n<0 ) {
throw new IllegalArgumentException();
}
modulus = n;
if (n==1 ) {
return ;
}
// Initialize the multiplier and offset
multiplier = (int ) Math.sqrt(n);
while (gcd(multiplier, n) != 1 ) {
if (++multiplier == n) {
multiplier = 1 ;
}
}
}
/**
* Returns the integer to which this permuter maps the specified integer .
* The specified integer must be between 0 and n - 1 , and the returned
* integer will be as well .
*/
public int map(int i) {
return (multiplier * i + addend) % modulus;
}
/**
* Calculate GCD of a and b , which are assumed to be non - negative .
*/
private static int gcd(int a, int b) {
while (b != 0 ) {
int tmp = a % b;
a = b;
b = tmp;
}
return a;
}
/**
* Simple test . Takes modulus on command line and prints out permutation .
*/
public static void main(String[] args) {
int modulus = Integer.parseInt(args[0 ]);
Permuter p = new Permuter(modulus);
for (int i=0 ; i<modulus; i++) {
System.out.print(p.map(i)+" " );
}
System.out.println();
}
}
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