Class Shuffle

java.lang.Object
  Shuffle

public class Shuffle
extends java.lang.Object

Shuffle.java
Solution for CS 201 HW 1 problem 3
Program to calculate the number of perfect shuffles that it takes to return an array to its starting position

Constructor Summary

Shuffle()

Method Summary

static int[]	identity(int L) Creates an identity array of the given size
static java.lang.String	intArrayToString(int[] a) Method for debugging: converts int array into string
static boolean	isIdentity(int[] A) Tests whether a given array is the identity array
static void	main(java.lang.String[] args) Calls printShufflePeriods with lo = 2, hi = 100.
static int[]	perfectShuffle(int[] A) Performs a perfect shuffle, alternating cards from the first and second halves of the deck
static void	printShufflePeriods(int lo, int hi) Prints the shuffle periods for all even integers between lo and hi (inclusive) Uses the form shufflePeriod(k)=P
static int	shufflePeriod(int L) Counts the number of perfect shuffles required to go from the identity array back to the identity array

Methods inherited from class java.lang.Object

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

Constructor Detail

Shuffle

public Shuffle()

Method Detail

main

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

Calls printShufflePeriods with lo = 2, hi = 100. Essentially used for testing

printShufflePeriods

public static void printShufflePeriods(int lo,
                                       int hi)

Prints the shuffle periods for all even integers between lo and hi (inclusive)
Uses the form shufflePeriod(k)=P

Parameters:

lo - the smallest array size to check the shuffle period of

hi - the greatest array size to check the shuffle period of

Precondition:

lo and hi should both be even, with lo <= hi

shufflePeriod

public static int shufflePeriod(int L)

Counts the number of perfect shuffles required to go from the identity array back to the identity array

Parameters:

L - the length of the deck to be shuffled

Returns:

the number of perfect shuffles to return to the identity array

perfectShuffle

public static int[] perfectShuffle(int[] A)

Performs a perfect shuffle, alternating cards from the first and second halves of the deck

Parameters:

A - the array to be shuffled

Returns:

the shuffled array

identity

public static int[] identity(int L)

Creates an identity array of the given size

Parameters:

L - the length of the identity array to be created

Returns:

an identity array of length L

isIdentity

public static boolean isIdentity(int[] A)

Tests whether a given array is the identity array

Parameters:

A - the array to be compared to the identity array

Returns:

true if the array is the identity array, false otherwise

intArrayToString

public static java.lang.String intArrayToString(int[] a)

Method for debugging: converts int array into string

Parameters:

a - the array to be converted

Returns:

a comma delimited string within brackets with each element of the int array