org.paukov.combinatorics3.SimpleSubSetIterator Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of combinatoricslib3 Show documentation

Simple java library to generate permutations, combinations and other combinatorial sequences

There is a newer version: 3.4.0

/**
 * Combinatorics Library 3
 * Copyright 2009-2016 Dmytro Paukov [email protected]
 */
package org.paukov.combinatorics3;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * Iterator over the all subsets
 *
 * @author Dmytro Paukov
 * @version 3.1.0
 * @see SubSetGenerator
 *
 * @param 
 *            Type of the elements of the subsets
 */
class SimpleSubSetIterator implements Iterator> {

    private final SimpleSubSetGenerator generator;
    private final int length;

    private List currentSubSet = null;
    private long currentIndex = 0;

    /**
     * internal bit vector, representing the subset
     */
    private int[] bitVector = null;


    SimpleSubSetIterator(final SimpleSubSetGenerator generator) {
        this.generator = generator;
        this.length = generator.originalVector.size();
        this.currentSubSet = new ArrayList<>();
        this.bitVector = new int[length + 2];
        this.currentIndex = 0;
    }

    /**
     * Returns true if iteration is done, otherwise false
     *
     * @see Iterator#hasNext()
     */
    @Override
    public boolean hasNext() {
        return bitVector[length + 1] != 1;
    }

    /**
     * Returns the next subset if it is available
     *
     * @see Iterator#next()
     */
    @Override
    public List next() {
        currentIndex++;
        currentSubSet.clear();
        for (int index = 1; index <= length; index++) {
            if (bitVector[index] == 1) {
                T value = this.generator.originalVector.get(index - 1);
                currentSubSet.add(value);
            }
        }
        int i = 1;
        while (bitVector[i] == 1) {
            bitVector[i] = 0;
            i++;
        }
        bitVector[i] = 1;

        return new ArrayList<>(currentSubSet);
    }


    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }


    @Override
    public String toString() {
        return "SimpleSubSetIterator=[#" + currentIndex + ", " + currentSubSet + "]";
    }

}