From dda0bcd654c8c97193efdeb031e9c1738120df2b Mon Sep 17 00:00:00 2001
From: Oshgnacknak <osh@oshgnacknak.de>
Date: Mon, 30 Aug 2021 15:39:15 +0200
Subject: [PATCH] Implement removeEverySecond

---
 .../prep/array/FullyUsedArrayProcessor.java     |  8 +++++++-
 test/aud/exam/prep/SequenceProcessorTest.java   | 17 +++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/aud/exam/prep/array/FullyUsedArrayProcessor.java b/src/aud/exam/prep/array/FullyUsedArrayProcessor.java
index 7e5a292..38b63d7 100644
--- a/src/aud/exam/prep/array/FullyUsedArrayProcessor.java
+++ b/src/aud/exam/prep/array/FullyUsedArrayProcessor.java
@@ -272,7 +272,13 @@ public class FullyUsedArrayProcessor<T> implements SequenceProcessor<T, FullyUse
 
     @Override
     public void removeEverySecond(FullyUsedArray<T> array) {
-        throw new UnsupportedOperationException();
+        T[] newArray = Arrays.newArray(array.theArray.length - array.theArray.length / 2);
+
+        for (int i = 0; i < newArray.length; i++) {
+            newArray[i] = array.theArray[2*i];
+        }
+
+        array.theArray = newArray;
     }
 
     @Override
diff --git a/test/aud/exam/prep/SequenceProcessorTest.java b/test/aud/exam/prep/SequenceProcessorTest.java
index 2ce9e1b..9bc9e9a 100644
--- a/test/aud/exam/prep/SequenceProcessorTest.java
+++ b/test/aud/exam/prep/SequenceProcessorTest.java
@@ -5,6 +5,7 @@ import org.junit.jupiter.params.provider.ArgumentsSource;
 
 import java.util.*;
 import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -404,6 +405,22 @@ public abstract class SequenceProcessorTest<S> {
         assertIterableEquals(list, processor.iterate(s));
     }
 
+    @ParameterizedTest
+    @ArgumentsSource(ListProvider.class)
+    void testThat_removeEverySecondWorks(List<Integer> list) {
+        S s = processor.create(list);
+
+        var everyFirst = IntStream
+            .iterate(0, i -> i < list.size(), i -> i+2)
+            .mapToObj(list::get)
+            .collect(Collectors.toList());
+
+        processor.removeEverySecond(s);
+
+        assertTrue(processor.check(s));
+        assertIterableEquals(everyFirst, processor.iterate(s));
+    }
+
     @ParameterizedTest
     @ArgumentsSource(ListProvider.class)
     void testThat_doubleAllKeysWorks(List<Integer> list) {