/**
@author  Scott Marshall
@author  University of Glasgow, MSc IT Project 2001
@author  Building an OnLine Course in Computing Fundamentals
*/


package ukacgla_KMap;
import java.util.*;


/** 
Provides Random numbers generator to fill the k map.
The random numbers generated are stored in an array. 
*/
abstract public class KMap_Random {

	//instance variables
	private Random rng;	
	private int[] randomNumbers;
	private int noRequired;


	/**
	Creates a new Random number generator, creates an array of specified size and generates
	required number of numbers (either 0 or 1) to fill the array. 
	*/
	public KMap_Random(int n){
		rng = new Random();
		noRequired = n;
		randomNumbers = new int[noRequired];
		genArray();
	
	}
	
	
	
	/** Generate  required number of numbers (either 0 or 1) and store these in array. */
	public void genArray()	{
		for(int i = 0 ; i < noRequired ; i++){
			randomNumbers[i] = rng.nextInt(2);
		}
	}


	/** Returns the random number stored at the specified index.*/ 
	public int getRandom(int n)	{
		return randomNumbers[n];
	}
	
	/**
	Generates a random number between 0(inclusive) and n(exclusive)
	If n is zero, will throw new IllegalArgumentException("n must be positive");
	*/
	public int genSingle(int n)	{
		int r = rng.nextInt(n);
		return r;
	}


	/**
	Will copy the elements of a vector into a new Vector, then return the new vector.
	The new Vector has the same number of elements as the original, but in a different order
	*/
	public Vector randomise(Vector original) {	

		Vector copy = new Vector();
		int reqSize = original.size();


		while (copy.size() < reqSize )	{  
			int source = genSingle(original.size());
			copy.add(original.get(source));
			original.removeElementAt(source);
			original.trimToSize();
		}

		return copy;

	}//ends randomise


}