// Copyright by Barry G. Becker, 2012. Licensed under MIT License: http://www.opensource.org/licenses/MIT
package com.barrybecker4.puzzle.tantrix.solver.path.permuting;
import com.barrybecker4.common.math.MathUtil;
import com.barrybecker4.puzzle.tantrix.solver.path.PathType;
import com.barrybecker4.puzzle.tantrix.solver.path.TantrixPath;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
/**
* Mix tiles of the same type without changing the primary originalPath.
*
* @author Barry Becker
*/
public class SameTypeTileMixer {
private static final int MAX_ITER = 20;
private PathType type;
private TantrixPath originalPath;
/**
* Constructor
* @param type one of the 3 path types
* @param path the path to create permutations of.
*/
public SameTypeTileMixer(PathType type, TantrixPath path) {
this.type = type;
this.originalPath = path;
}
public List<TantrixPath> findPermutedPaths() {
TilesOfTypeIndices indices = new TilesOfTypeIndices(type, originalPath);
return findPermutedPaths(indices);
}
private List<TantrixPath> findPermutedPaths(TilesOfTypeIndices indices) {
List<TantrixPath> permutedPaths = new LinkedList<TantrixPath>();
PathTilePermuter permuter = new PathTilePermuter(originalPath);
if (indices.size() == 2) {
List<Integer> newOrder = new ArrayList<Integer>(indices);
Collections.reverse(newOrder);
TantrixPath permutedPath = permuter.permute(newOrder, indices);
permutedPaths.add(permutedPath);
}
else if (indices.size() > 2) {
// add the original originalPath for now, to be sure we do not duplicated it, but return at end.
permutedPaths.add(originalPath);
int numIter = Math.min(originalPath.size() + 1, MAX_ITER);
for (int i = 0; i < numIter; i++) {
List<Integer> newOrder = new ArrayList<Integer>(indices);
Collections.shuffle(newOrder, MathUtil.RANDOM);
TantrixPath permutedPath = permuter.permute(newOrder, indices);
if (!permutedPaths.contains(permutedPath)) {
permutedPaths.add(permutedPath);
}
}
permutedPaths.remove(0);
}
return permutedPaths;
}
}