part 1 is done

src/main/java/spliterators/part1/exercise/RectangleSpliterator.java

@@ -9,9 +9,9 @@ public class RectangleSpliterator extends Spliterators.AbstractIntSpliterator {
 
     private final int innerLength;
     private final int[][] array;
-    private final int startOuterInclusive;
+    private int startOuterInclusive;
     private final int endOuterExclusive;
-    private final int startInnerInclusive;
+    private int startInnerInclusive;
 
     public RectangleSpliterator(int[][] array) {
         this(array, 0, array.length, 0);
@@ -29,18 +29,33 @@ private RectangleSpliterator(int[][] array, int startOuterInclusive, int endOute
 
     @Override
     public OfInt trySplit() {
-        // TODO
-        throw new UnsupportedOperationException();
+        final int outerLen = endOuterExclusive - startOuterInclusive;
+        if (outerLen <= 1) return null;
+        final int outerMid = startOuterInclusive + outerLen / 2;
+
+        final RectangleSpliterator res = new RectangleSpliterator(array, startOuterInclusive, outerMid, startInnerInclusive);
+        startOuterInclusive = outerMid;
+        return res;
     }
 
+
     @Override
     public long estimateSize() {
-        return ((long) endOuterExclusive - startOuterInclusive)*innerLength - startInnerInclusive;
+        return ((long) endOuterExclusive - startOuterInclusive) * innerLength - startInnerInclusive;
     }
 
     @Override
     public boolean tryAdvance(IntConsumer action) {
-        // TODO
-        throw new UnsupportedOperationException();
+        if (startOuterInclusive >= endOuterExclusive
+                && startInnerInclusive >= innerLength)
+            return false;
+
+        for (int i = startInnerInclusive; i < innerLength; i++) {
+            final int value = array[startOuterInclusive][startInnerInclusive];
+            startInnerInclusive++;
+            action.accept(value);
+        }
+
+        return true;
     }
 }