Class PerfectShuffler

java.lang.Object

PerfectShuffler

public class PerfectShuffler
extends java.lang.Object

PerfectShuffler - class modeling perfect (a.k.a. faro) in- and out-shuffles.

A perfect shuffle is one where the deck is cut perfectly in half and then "riffled" together alternating one card from each half like the teeth of a zipper before being pushed together. This is considered to be one of the most difficult sleights of hand in card magic, and it allows the performer to control the positions of all cards in the deck, rearranging the permutation in unexpected ways. There are two perfect shuffles that differ according to whether the first card down comes from the top or bottom half. A perfect out-shuffle leaves the top card on top, that is, outside the deck. A perfect in-shuffle leaves the top card at the second card, that is, inside the deck.

public String toString() specification: toString should return a comma-and-space-separated list of the current permutation of deck indices (0-51). The easiest way to do this is to make use of the Arrays.toString() method and return the result without the first ("[") and last ("]") characters.

Constructor Summary

Constructors

Constructor and Description
PerfectShuffler() Initialize an array with 52-card deck indices such that index i contains integer i.

Method Summary

Modifier and Type	Method and Description
int	getIndexAt(int index) Return the current card index at the given index.
void	inShuffle() Perform a perfect in-shuffle on the deck indices.
static void	main(java.lang.String[] args) Create a PerfectShuffler object and print it.
void	outShuffle() Perform a perfect out-shuffle on the deck indices.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PerfectShuffler

public PerfectShuffler()

Initialize an array with 52-card deck indices such that index i contains integer i.

Method Detail

inShuffle

public void inShuffle()

Perform a perfect in-shuffle on the deck indices. For example, an in-shuffled initial deck ordered [0, 1, 2, 3, ..., 50, 51]) should be reordered [26, 0, 27, 1, ..., 51, 25].

outShuffle

public void outShuffle()

Perform a perfect out-shuffle on the deck indices. For example, an out-shuffled initial deck ordered [0, 1, 2, 3, ..., 50, 51]) should be reordered [0, 26, 1, 27, ..., 25, 51].

getIndexAt

public int getIndexAt(int index)

Return the current card index at the given index. For example, if getIndexAt(2) returns 27, this would indicate that that current card at the third position started at the 28th position before the sequence of in- and/or out-shuffles.

Parameters:

index - the given deck index

Returns:

the current card index at that given index.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

main

public static void main(java.lang.String[] args)

Create a PerfectShuffler object and print it. Then read one line at a time from the standard input until there are no more lines. For each line with the command "i", perform a perfect in-shuffle on the PerfectShuffler object and print it. For each line with the command "o", perform a perfect out-shuffle on the PerfectShuffler object and print it.

Parameters:

args - (unused)