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package algs22;
import stdlib.*;
import java.security.SecureRandom;
/* ***********************************************************************
* Compilation: javac SecureShuffle.java
* Execution: java SecureShuffle < list.txt
*
* Reads in a list of strings and prints them in random order.
* Our shuffling algorithm guarantees to rearrange the elements
* in uniformly random order, under the assumption that Math.random()
* generates independent and uniformly distributed numbers between
* 0 and 1.
*
* % more cards.txt
* 2C 3C 4C 5C 6C 7C 8C 9C 10C JC QC KC AC
* 2D 3D 4D 5D 6D 7D 8D 9D 10D JD QD KD AD
* 2H 3H 4H 5H 6H 7H 8H 9H 10H JH QH KH AH
* 2S 3S 4S 5S 6S 7S 8S 9S 10S JS QS KS AS
*
* % java Shuffle < cards.txt
* 6H
* 9C
* 8H
* 7C
* JS
* ...
* KH
*
*************************************************************************/
public class XSecureShuffle {
public static void main(String[] args) {
// read in the data
String[] a = StdIn.readAll().split("\\s+");
int N = a.length;
// create random array of real numbers between 0 and 1
SecureRandom random = new SecureRandom();
Double[] r = new Double[N];
for (int i = 0; i < N; i++) {
r[i] = random.nextDouble();
}
// shuffle and get resulting permutation
int[] index = Merge.indexSort(r);
// print permutation
for (int i = 0; i < N; i++)
StdOut.println(a[index[i]]);
}
}
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