Added NumberUtils to generate combinations of numbers.

gemp-lotr/gemp-lotr-server/src/main/java/com/gempukku/lotro/tournament/NumberUtils.java

@@ -0,0 +1,59 @@
+package com.gempukku.lotro.tournament;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class NumberUtils {
+    /**
+     * Chooses a combination of count numbers from 0<=i<maxNumber, without repetitions. This method will return different
+     * result for every "iteration" value (iteration starts at 0). If there is no more possible combinations, it will
+     * return null
+     *
+     * @param count
+     * @param maxNumber
+     * @param iteration
+     * @return
+     */
+    public static int[] selectOrderedCombinationOfNumbers(int count, int maxNumber, int iteration) {
+        if (count > maxNumber)
+            throw new IllegalArgumentException("Count cannot be bigger than maxNumber");
+
+        int left = iteration;
+        int[] indexes = new int[count];
+        for (int i = 0; i < count; i++) {
+            int resultWithOffset = left % (maxNumber - i);
+            indexes[i] = resultWithOffset;
+            left = left / (maxNumber - i);
+        }
+        if (left>0)
+            return null;
+        else {
+            List<Integer> values = new ArrayList<Integer>(maxNumber);
+            for (int i=0; i<maxNumber; i++)
+                values.add(i);
+
+            int[] result = new int[count];
+            for (int i=0; i<count; i++)
+                result[count-i-1] = values.remove(indexes[i]);
+
+            return result;
+        }
+    }
+
+    public static void main(String[] args) {
+        int count = 3;
+        int maxNumber = 5;
+        
+        int iteration = 0;
+        while (true) {
+            int[] result = selectOrderedCombinationOfNumbers(count, maxNumber, iteration);
+            if (result == null) {
+                System.out.println("Combinations: "+iteration);
+                break;
+            }
+            System.out.println(Arrays.toString(result));
+            iteration++;
+        }
+    }
+}