edu.umd.cfar.lamp.viper.util
Class Permuter

java.lang.Object
  edu.umd.cfar.lamp.viper.util.Permuter

public class Permuter

extends java.lang.Object

This class takes in an array of Objects and runs through all possible permutations.

Author:

David Mihalcik

See Also:

Combinator

Constructor Summary

Permuter(java.lang.Object[] stringToPermute)
Constructs a new Permuter to iterate over all permutations of the given string.

Method Summary

static int	factorial(int x) Gets the factorial of an integer.
java.lang.Object[]	getNextPermutation() Based on Dijkstra's method for doing this sort of thing.
java.lang.String	toString() Gets a string representation of the current permutation.

Methods inherited from class java.lang.Object

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

Constructor Detail

Permuter

public Permuter(java.lang.Object[] stringToPermute)

Constructs a new Permuter to iterate over all permutations of the given string.

Parameters:

stringToPermute - The Objects to rearrange.

Method Detail

factorial

public static int factorial(int x)

Gets the factorial of an integer.

Parameters:

x - The integer.

Returns:

x!

getNextPermutation

public java.lang.Object[] getNextPermutation()

Based on Dijkstra's method for doing this sort of thing.

    private void getNext()
    {
        int i = N - 1;
        while (Value[i-1] >= Value[i])
            i = i-1;

        int j = N;
        while (Value[j-1] <= Value[i-1])
            j = j-1;

        swap(i-1, j-1);
        i++; j = N;
        while (i < j) {
            swap(i-1, j-1);
            i++;
            j--;
        }
    }
 

Returns:

The next arrangement.

toString

public java.lang.String toString()

Gets a string representation of the current permutation.

Returns:

The current permutation bracketed and with spaces.