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

package pathgame.algorithm;

/** Class for generating all possible permutations of travelling salesman paths
 *
 */
public class Permutation {
    private int size;
    private int[] vals;
    private int[] minVals;
    private int minCost = Integer.MAX_VALUE;
    private int thingsPerPos;

    /** Creates a new Permutation based on the given parameters
     *
     * @param listSize size of the list the permutation is for
     * @param thingsPerPos number of list items per permutation position - for pairs: 2, for single items: 1
     */
    public Permutation(int listSize, int thingsPerPos) {
        this.thingsPerPos = thingsPerPos;
        this.size = (listSize/thingsPerPos) - 1;
        vals = new int[size];

    }

    /** Returns the offset stored at the given position
     *
     * @param pos position of the permutation from which the value should be returned
     * @return an offset of the Permutation
     */
    public int getValAtPos (int pos) {
        return vals[pos];
    }

    /** Returns true if the offset value at the given position can't be increased further
     *
     * @param pos position of the permutation that should be checked
     * @return whether offset at the given position is at its maximum
     */
    public boolean isPosAtMax (int pos) {
        if(vals[pos] == getMaxOfPos(pos)) {
            return true;
        }
        return false;
    }

    /** Returns the maximum value an offset can have at the given position
     *
     * @param pos position of the permutation that should be checked
     * @return the maximum value an offset can have at the given position
     */
    public int getMaxOfPos (int pos) {
        return thingsPerPos * (size - pos);
    }

    /** Returns the size of the permutation
     *
     * @return the size of the permutation
     */
    public int size() {
        return size;
    }

    /** Increases the offset at the given position by 1 and sets all offsets of higher positions back to 0
     *
     * @param pos position of the permutation that should be increased
     */
    public void increaseAtPos (int pos) {
        vals[pos]++;
        for(int i = pos+1; i < size; i++) {
            vals[i] = 0;
        }
    }

    /** Returns the minimum cost stored in this Permutation
     *
     * @return the minimum cost stored in this Permutation
     */
    public int getMinCost() {
        return minCost;
    }

    /** Sets the minimum cost stored in this Permutation
     *
     * @param minCost the new minimum cost to be set
     */
    public void setMinCost(int minCost) {
        this.minCost = minCost;
        minVals = vals.clone();
    }

    /** Makes the current permutation the new minimum permutation to be stored
     *
     */
    public void makePermutMinimal() {
        vals = minVals.clone();
    }

    /** Prints the current permutation
     *
     */
    public void printPermut() {
        for(int i = 0; i < size; i++) {
            System.out.print(vals[i] + " ");
        }
        System.out.println();
    }

    /** Prints the stored minimum permutation
     *
     */
    public void printMinPermut() {
        for(int i = 0; i < size; i++) {
            System.out.print(minVals[i] + " ");
        }
        System.out.println();
    }
}