path-game/src/pathgame/algorithm/OddDegreeList.java

package pathgame.algorithm;

import java.util.ArrayList;

/** Class for storing and managing a list of graph vertexes with odd degrees
 *
 */
public class OddDegreeList {
    private ArrayList<Integer> items = new ArrayList<>();
    private ArrayList<Boolean> itemUsed = new ArrayList<>();

    /** Adds a vertex to the list
     *
     * @param vertex index of the vertex in the list of all vertexes
     */
    public void add(int vertex) {
        items.add(vertex);
        itemUsed.add(false);
    }

    /** Returns the size of the list of vertexes
     *
     * @return the size of the list of vertexes
     */
    public int size() {
        return items.size();
    }

    /** Resets which vertexes have already been used for the permutation
     *
     */
    public void resetUsed() {
        for(int i = 0; i < itemUsed.size(); i++) {
            itemUsed.set(i, false);
        }
    }

    /** Returns the next unused vertex after the given offset
     *
     * @param offSet number of unused vertexes that are skipped before returning a vertex
     * @return the next unused vertex after the offset
     */
    public int getUnused(int offSet) {
        return items.get(getOffsetPos(offSet));
    }

    /** Makes an unused vertex used after the given offset
     *
     * @param offSet number of unused vertexes that are skipped before making the vertex used
     * @return the index of the vertex that was made used
     */
    public int makeOffsetUsed(int offSet) {
        int pos = getOffsetPos(offSet);
        itemUsed.set(pos, true);
        return pos;
    }

    /** makes the vertex at the given position unused
     *
     * @param pos index of the vertex that is made unused
     */
    public void makeUnused(int pos) {
        itemUsed.set(pos, false);
    }

    private int getOffsetPos(int offSet) {
        int foundValid = 0;

        for (int i = 0; i < items.size(); i++) {
            if (!itemUsed.get(i)) {
                if (offSet == foundValid) {
                    return i;
                }
                foundValid++;
            }
        }
        return -1;
    }
}