content: /*************************************************************************
   *  Compilation:  javac Shuffle.java
   *  Execution:    java Shuffle < list.txt
   *  Data files:   http://algs4.cs.princeton.edu/11model/cards.txt
   *  
   *  Reads in a list of strings and prints them in random order.
   *  The Knuth (or Fisher-Yates) 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 Shuffle { 
      public static void main(String[] args) {
  
          // read in the data
          String[] a = StdIn.readAll().split("\\s+");
          int N = a.length;
  
          // shuffle
          for (int i = 0; i < N; i++) {
              // int from remainder of deck
              int r = i + (int) (Math.random() * (N - i));
              String swap = a[r];
              a[r] = a[i];
              a[i] = swap;
          }
  
          // print permutation
          for (int i = 0; i < N; i++)
              StdOut.println(a[i]);
      }
  }
  