first Powersort successful implementation, Translation of the notebook.

.idea/misc.xml

@@ -3,5 +3,5 @@
   <component name="FrameworkDetectionExcludesConfiguration">
     <file type="web" url="file://$PROJECT_DIR$" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_X" project-jdk-name="jbr-17" project-jdk-type="JavaSDK" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_X" project-jdk-name="23" project-jdk-type="JavaSDK" />
 </project>

app/src/main/java/de/uni_marburg/powersort/App.java

@@ -3,6 +3,11 @@
  */
 package de.uni_marburg.powersort;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import static de.uni_marburg.powersort.PowerSort.extendRun;
+
 public class App {
     public String getGreeting() {
         return "Let's bring Powersort to Java!";
@@ -10,5 +15,8 @@ public class App {
 
     public static void main(String[] args) {
         System.out.println(new App().getGreeting());
+        List<Integer> list = new ArrayList<>(List.of(5, 2, 8, 12, 1, 6));
+            extendRun(list, 0);
+            System.out.println(list);
     }
 }

app/src/main/java/de/uni_marburg/powersort/PowerSort.java

@@ -1,6 +1,8 @@
 package de.uni_marburg.powersort;
 
-import java.util.Comparator;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 
 class PowerSort<T> {
     /**
@@ -19,8 +21,229 @@ class PowerSort<T> {
      * @param workLen  usable size of work array
      * @since 1.8
      */
-    static <T> void sort(T[] a, int lo, int hi, Comparator<? super T> c,
+        private static int MERGE_COST = 0;
+
+        private static List<Integer> merge(List<Integer> run1, List<Integer> run2) {
+            List<Integer> result = new ArrayList<>();
+            while (!run1.isEmpty() && !run2.isEmpty()) {
+                if (run1.get(0) < run2.get(0)) {
+                    result.add(run1.remove(0));
+                } else {
+                    result.add(run2.remove(0));
+                }
+            }
+            result.addAll(run1);
+            result.addAll(run2);
+            return result;
+        }
+
+        private static void mergeInplace(List<Integer> a, int i, int m, int j) {
+            System.out.printf("Merge(%d, %d, %d)%n", i, m, j);
+            MERGE_COST += j - i;
+            List<Integer> sublist = merge(
+                    new ArrayList<>(a.subList(i, m)),
+                    new ArrayList<>(a.subList(m, j))
+            );
+            for (int k = 0; k < sublist.size(); k++) {
+                a.set(i + k, sublist.get(k));
+            }
+        }
+
+        static int extendRun(List<Integer> a, int i) {
+            if (i == a.size() - 1) {
+                return i + 1;
+            }
+            int j = i + 1;
+            if (a.get(i) <= a.get(j)) {
+                while (j < a.size() && a.get(j - 1) <= a.get(j)) {
+                    j++;
+                }
+            } else {
+                while (j < a.size() && a.get(j - 1) > a.get(j)) {
+                    j++;
+                }
+                List<Integer> sublist = a.subList(i, j);
+                Collections.reverse(sublist);
+            }
+            return j;
+        }
+
+        private static int extendRunIncreasingOnly(List<Integer> a, int i) {
+            if (i == a.size() - 1) {
+                return i + 1;
+            }
+            int j = i + 1;
+            while (j < a.size() && a.get(j - 1) <= a.get(j)) {
+                j++;
+            }
+            return j;
+        }
+
+        public static int power(int[] run1, int[] run2, int n) {
+            int i1 = run1[0], n1 = run1[1];
+            int i2 = run2[0], n2 = run2[1];
+
+            assert i1 >= 0;
+            assert i2 == i1 + n1;
+            assert n1 >= 1 && n2 >= 1;
+            assert i2 + n2 <= n;
+// ask question about this whether it should be double or int
+            int a = (int) ((i1 + n1 / 2.0) / n);
+            int b = (int) ((i2 + n2 / 2.0) / n);
+
+            int l = 0;
+            while (Math.floor(a * Math.pow(2, l)) == Math.floor(b * Math.pow(2, l))) {
+                l++;
+            }
+            return l;
+        }
+
+        public static int powerFast(int[] run1, int[] run2, int n) {
+            int i1 = run1[0], n1 = run1[1];
+            int i2 = run2[0], n2 = run2[1];
+
+            int a = 2 * i1 + n1;
+            int b = a + n1 + n2;
+
+            int l = 0;
+            while (true) {
+                l++;
+                if (a >= n) {
+                    assert b >= a;
+                    a -= n;
+                    b -= n;
+                } else if (b >= n) {
+                    break;
+                }
+                assert a < b && b < n;
+                a <<= 1;
+                b <<= 1;
+            }
+            return l;
+        }
+
+        public static void mergeTopmost2(List<Integer> a, List<int[]> runs) {
+            assert runs.size() >= 2;
+// is this right?
+            int[] Y = runs.get(runs.size() - 2);
+            int[] Z = runs.get(runs.size() - 1);
+
+            assert Z[0] == Y[0] + Y[1];
+
+            mergeInplace(a, Y[0], Z[0], Z[0] + Z[1]);
+
+            runs.set(runs.size() - 2, new int[]{Y[0], Y[1] + Z[1], Y[2]});
+            runs.remove(runs.size() - 1);
+        }
+
+        public static void powerSort(List<Integer> a) {
+            int n = a.size();
+            int i = 0;
+            List<int[]> runs = new ArrayList<>();
+
+            int j = extendRun(a, i);
+            runs.add(new int[]{i, j - i, 0});
+            i = j;
+
+            while (i < n) {
+                j = extendRun(a, i);
+                int p = power(runs.get(runs.size() - 1), new int[]{i, j - i}, n);
+
+                while (p <= runs.get(runs.size() - 1)[2]) {
+                    mergeTopmost2(a, runs);
+                }
+
+                runs.add(new int[]{i, j - i, p});
+                i = j;
+            }
+
+            while (runs.size() >= 2) {
+                mergeTopmost2(a, runs);
+            }
+        }
+    }
+
+//        // Example usage
+//        public static void main(String[] args) {
+//            List<Integer> list = new ArrayList<>(List.of(5, 2, 8, 12, 1, 6));
+//            extendRun(list, 0);
+//            System.out.println(list);
+//        }
+
+
+
+  /*  static <T> void sort(T[] a, int lo, int hi, Comparator<? super T> c,
                          T[] work, int workBase, int workLen) {
         assert c != null && a != null && lo >= 0 && lo <= hi && hi <= a.length;
+    }*/
+/*
+    public static final int MIN_MERGE=24;
+    public int mergeCost=0;
+    private final T []sortedArray;
+
+    public PowerSort(T[] sortedArray) {
+        super();
+        this.sortedArray = sortedArray;
     }
+
+    ArrayList<Integer> run1 = new ArrayList<>();
+    ArrayList<Integer> run2 = new ArrayList<>();
+
+    private AbstractList<Integer> merge(ArrayList <Integer> run1, ArrayList<Integer> run2) {
+       ArrayList<Integer> result = new ArrayList<>();
+
+        while(run1.size() > 0 && run2.size() >0) {
+            if (run1.getFirst()<run2.getFirst()){
+                result.add(run1.getFirst());
+                run1.removeFirst();
+            }else {
+                result.add(run2.getFirst());
+                run2.removeFirst();
             }
+            result.addAll(run1);
+            result.addAll(run2);
+        }
+        return result;
+    }
+
+    public void mergeInplace(int[] a, int[] i, int[] m, int[] j) {
+        //System.out.println("merge(" + i + "," + m + "," + j + ")");
+
+            System.out.printf("Merge(%d, %d, %d)%n", i, m, j);
+      //    this.mergeCost += j - i;
+
+
+        for(int s =0; s < i.length && s< j.length ; s++) {
+
+
+//            int[] leftSubarray = copyOfRange(a, i, m);
+//            int[] rightSubarray = copyOfRange(a, m, j);
+//            int[] mergedSubarray = merge(leftSubarray, rightSubarray);
+//            System.arraycopy(mergedSubarray, 0, a, i, mergedSubarray.length);
+////            mergeCost += j[s] - i[s];
+//            System.arraycopy(merge(Arrays.copyOfRange(a, i, m), Arrays.copyOfRange(a, m, j)), 0, a, i, j - i);
+//            a[i:j]=merge(a[i:m],a[m:j]);
+        }
+
+    }
+
+
+
+    public void power(int run1,int run2, int n) {
+        int i = run1;
+        int n1 = run1;
+        int j = run2;
+        int n2 = run2;
+        int a=(i + n1/2) / n;
+        int b=(j + n2/2) / n;
+        int l =0;
+        //while( Math.floor(a * 2**1)){
+       //     Math.floor(b * );
+      //  }
+
+    }
+
+    public void sorting(final int[] Array, final int left, final int right) {
+
+
+    }*/