Cleaned up counter classes.

src/main/kotlin/be/nielandt/CrossSolverBase.kt

@@ -1,5 +1,7 @@
 package be.nielandt
 
+import be.nielandt.counter.CounterBasic
+
 class CrossSolverBase : CrossSolver() {
     /**
      * Solve the minimal cross for all colors.
@@ -10,7 +12,7 @@ class CrossSolverBase : CrossSolver() {
         for (moveCount in 1..8) {
             // build a counter of moveCount big
             println("allCrossMoveCount basic doing $moveCount")
-            val counter = Counter(moveCount, 18)
+            val counter = CounterBasic(moveCount)
 
             // count up, each state of the counter corresponds to a combination of moves
             do {

src/main/kotlin/be/nielandt/CrossSolverUpgraded.kt

@@ -1,5 +1,7 @@
 package be.nielandt
 
+import be.nielandt.counter.CounterBasic
+
 /**
  * This solver avoids redoing edgemodel manipulations. Should be equivalent to X nested for loops.
  */
@@ -10,7 +12,7 @@ class CrossSolverUpgraded : CrossSolver() {
         for (moveCount in 1..8) {
             println("all cross move count upgrade doing $moveCount")
             // build a counter of moveCount big
-            val counter = Counter(moveCount, 18)
+            val counter = CounterBasic(moveCount)
             val edgeModelFactory = EdgeModelFactory(edgeModel, counter)
 
             while (edgeModelFactory.hasNext()) {

src/main/kotlin/be/nielandt/CrossSolverUpgradedSkip.kt

@@ -1,5 +1,7 @@
 package be.nielandt
 
+import be.nielandt.counter.CounterSkip
+
 /**
  * This solver avoids redoing edgemodel manipulations. Should be equivalent to X nested for loops.
  */

src/main/kotlin/be/nielandt/EdgeModelFactory.kt

@@ -1,5 +1,7 @@
 package be.nielandt
 
+import be.nielandt.counter.Counter
+
 /**
  * This thing helps us to create edgemodels using a counter. The advantage is that the edgemodel doesn't need to be calculated
  * completely from scratch: previous states are kept, so if, e.g., the third digit changes in the counter (of length 5),

src/main/kotlin/be/nielandt/counter/Counter.kt

@@ -1,9 +1,9 @@
-package be.nielandt
+package be.nielandt.counter
 
 /**
  * Counter for X digits of a given base.
  */
-open class Counter(size: Int, val base: Int = 18) {
+open abstract class Counter(size: Int, val base: Int = 18) {
 
     /**
      * Empty counter, all 0 values for each digit.
@@ -17,26 +17,9 @@ open class Counter(size: Int, val base: Int = 18) {
      var lastModifiedIndex: Int = 0
 
     /**
-     * Increase the counter.
-     *
-     * @return true if the increase happened, false if we hit the ceiling.
+     * Increase the counter one step. True if it succeeded and a new value is there, false if we've reached the end.
      */
-    open fun increase(): Boolean {
-        if (atMax()) {
-            return false
-        }
-        for (i in this.counter.size - 1 downTo 0) {
-            this.counter[i]++
-            this.lastModifiedIndex = i
-            if (this.counter[i] == base) {
-                this.counter[i] = 0
-            } else {
-                // keep track of the digit index we're breaking on.
-                break
-            }
-        }
-        return true
-    }
+    abstract fun increase(): Boolean
 
     /**
      * How many digits does this counter contain?

src/main/kotlin/be/nielandt/counter/CounterBasic.kt

@@ -0,0 +1,38 @@
+package be.nielandt.counter
+
+import java.util.*
+
+/**
+ * Counter for X digits of a given base. Skips situations where faces are the same.
+ */
+class CounterBasic(size: Int) : Counter(size, 18) {
+
+    /**
+     * Increase the counter.
+     *
+     * @return true if the increase happened, false if we hit the ceiling.
+     */
+    override fun increase(): Boolean {
+        if (atMax()) {
+            return false
+        }
+        for (i in this.counter.size - 1 downTo 0) {
+            this.counter[i]++
+            this.lastModifiedIndex = i
+            if (this.counter[i] == base) {
+                this.counter[i] = 0
+            } else {
+                // keep track of the digit index we're breaking on.
+                break
+            }
+        }
+        return true
+    }
+}
+
+fun main(args: Array<String>) {
+    val counterSkip = CounterSkip(4)
+    while (counterSkip.increase()) {
+        println("counterSkip.counter = ${Arrays.toString(counterSkip.counter)}")
+    }
+}

src/main/kotlin/be/nielandt/counter/CounterSkip.kt

@@ -1,4 +1,4 @@
-package be.nielandt
+package be.nielandt.counter
 
 import java.util.*