refactor: simple improvements and cleanup for different sorts (#5320)

src/main/java/com/thealgorithms/sorts/CircleSort.java

@@ -7,25 +7,29 @@ public class CircleSort implements SortAlgorithm {
      */
     @Override
     public <T extends Comparable<T>> T[] sort(T[] array) {
-        int n = array.length;
+        if (array.length == 0) {
-        if (n == 0) {
             return array;
         }
-        while (doSort(array, 0, n - 1)) {
+        while (doSort(array, 0, array.length - 1)) {
         }
         return array;
     }
 
-    /* This method implements the cyclic sort recursive version
+    /**
+     * Recursively sorts the array in a circular manner by comparing elements
+     * from the start and end of the current segment.
+     *
+     * @param <T>   The type of elements in the array, which must be comparable
      * @param array The array to be sorted
-     * @param the left boundary of the part currently being sorted
+     * @param left  The left boundary of the current segment being sorted
-     * @param the right boundary of the part currently being sorted
+     * @param right The right boundary of the current segment being sorted
+     * @return true if any elements were swapped during the sort; false otherwise
      */
-    private <T extends Comparable<T>> Boolean doSort(T[] array, int left, int right) {
+    private <T extends Comparable<T>> boolean doSort(final T[] array, final int left, final int right) {
         boolean swapped = false;
 
         if (left == right) {
-            return Boolean.FALSE;
+            return false;
         }
 
         int low = left;
@@ -45,10 +49,10 @@ public class CircleSort implements SortAlgorithm {
             swapped = true;
         }
 
-        int mid = left + (right - left) / 2;
+        final int mid = left + (right - left) / 2;
-        Boolean leftHalf = doSort(array, left, mid);
+        final boolean leftHalfSwapped = doSort(array, left, mid);
-        Boolean rightHalf = doSort(array, mid + 1, right);
+        final boolean rightHalfSwapped = doSort(array, mid + 1, right);
 
-        return swapped || leftHalf || rightHalf;
+        return swapped || leftHalfSwapped || rightHalfSwapped;
     }
 }

src/main/java/com/thealgorithms/sorts/OddEvenSort.java

@@ -13,29 +13,39 @@ public final class OddEvenSort implements SortAlgorithm {
      * Sorts the given array using the Odd-Even Sort algorithm.
      *
      * @param <T> the type of elements in the array, which must implement the Comparable interface
-     * @param arr the array to be sorted
+     * @param array the array to be sorted
      * @return the sorted array
      */
     @Override
-    public <T extends Comparable<T>> T[] sort(T[] arr) {
+    public <T extends Comparable<T>> T[] sort(T[] array) {
         boolean sorted = false;
         while (!sorted) {
-            sorted = true;
+            sorted = performOddSort(array);
+            sorted = performEvenSort(array) && sorted;
+        }
 
-            for (int i = 1; i < arr.length - 1; i += 2) {
+        return array;
-                if (arr[i].compareTo(arr[i + 1]) > 0) {
+    }
-                    SortUtils.swap(arr, i, i + 1);
+
+    private <T extends Comparable<T>> boolean performOddSort(T[] array) {
+        boolean sorted = true;
+        for (int i = 1; i < array.length - 1; i += 2) {
+            if (array[i].compareTo(array[i + 1]) > 0) {
+                SortUtils.swap(array, i, i + 1);
                 sorted = false;
             }
         }
+        return sorted;
+    }
 
-            for (int i = 0; i < arr.length - 1; i += 2) {
+    private <T extends Comparable<T>> boolean performEvenSort(T[] array) {
-                if (arr[i].compareTo(arr[i + 1]) > 0) {
+        boolean sorted = true;
-                    SortUtils.swap(arr, i, i + 1);
+        for (int i = 0; i < array.length - 1; i += 2) {
+            if (array[i].compareTo(array[i + 1]) > 0) {
+                SortUtils.swap(array, i, i + 1);
                 sorted = false;
             }
         }
-        }
+        return sorted;
-        return arr;
     }
 }

src/main/java/com/thealgorithms/sorts/SelectionSort.java

@@ -10,18 +10,17 @@ public class SelectionSort implements SortAlgorithm {
      */
     @Override
     public <T extends Comparable<T>> T[] sort(T[] array) {
-        // One by one move the boundary of the unsorted subarray
-        for (int i = 0; i < array.length - 1; i++) {
 
-            // Swap the remaining minimum element with the current element
+        for (int i = 0; i < array.length - 1; i++) {
-            SortUtils.swap(array, i, findIndexOfMin(array, i));
+            final int minIndex = findIndexOfMin(array, i);
+            SortUtils.swap(array, i, minIndex);
         }
         return array;
     }
 
-    private static <T extends Comparable<T>> int findIndexOfMin(T[] array, final int start) {
+    private static <T extends Comparable<T>> int findIndexOfMin(T[] array, final int startIndex) {
-        int minIndex = start;
+        int minIndex = startIndex;
-        for (int i = start + 1; i < array.length; i++) {
+        for (int i = startIndex + 1; i < array.length; i++) {
             if (array[i].compareTo(array[minIndex]) < 0) {
                 minIndex = i;
             }

src/main/java/com/thealgorithms/sorts/SimpleSort.java

@@ -1,51 +1,15 @@
 package com.thealgorithms.sorts;
 
 public class SimpleSort implements SortAlgorithm {
-
     @Override
     public <T extends Comparable<T>> T[] sort(T[] array) {
-        final int length = array.length;
+        for (int i = 0; i < array.length; i++) {
-
+            for (int j = i + 1; j < array.length; j++) {
-        for (int i = 0; i < length; i++) {
-            for (int j = i + 1; j < length; j++) {
                 if (SortUtils.less(array[j], array[i])) {
                     SortUtils.swap(array, i, j);
                 }
             }
         }
-
         return array;
     }
-
-    public static void main(String[] args) {
-        // ==== Int =======
-        Integer[] a = {3, 7, 45, 1, 33, 5, 2, 9};
-        System.out.print("unsorted: ");
-        SortUtils.print(a);
-        System.out.println();
-
-        new SimpleSort().sort(a);
-        System.out.print("sorted: ");
-        SortUtils.print(a);
-        System.out.println();
-
-        // ==== String =======
-        String[] b = {
-            "banana",
-            "berry",
-            "orange",
-            "grape",
-            "peach",
-            "cherry",
-            "apple",
-            "pineapple",
-        };
-        System.out.print("unsorted: ");
-        SortUtils.print(b);
-        System.out.println();
-
-        new SimpleSort().sort(b);
-        System.out.print("sorted: ");
-        SortUtils.print(b);
-    }
 }

src/main/java/com/thealgorithms/sorts/StrandSort.java

@@ -38,9 +38,9 @@ public final class StrandSort implements SortAlgorithm {
         List<T> result = new ArrayList<>();
         while (!list.isEmpty()) {
             final List<T> sorted = new ArrayList<>();
-            sorted.add(list.remove(0));
+            sorted.add(list.removeFirst());
             for (int i = 0; i < list.size();) {
-                if (sorted.get(sorted.size() - 1).compareTo(list.get(i)) <= 0) {
+                if (sorted.getLast().compareTo(list.get(i)) <= 0) {
                     sorted.add(list.remove(i));
                 } else {
                     i++;

src/test/java/com/thealgorithms/sorts/SimpleSortTest.java

@@ -1,66 +1,8 @@
 package com.thealgorithms.sorts;
 
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+public class SimpleSortTest extends SortingAlgorithmTest {
-
+    @Override
-import org.junit.jupiter.api.Test;
+    SortAlgorithm getSortAlgorithm() {
-
+        return new SimpleSort();
-public class SimpleSortTest {
-
-    private SimpleSort simpleSort = new SimpleSort();
-
-    @Test
-    public void simpleSortEmptyArray() {
-        Integer[] inputArray = {};
-        Integer[] outputArray = simpleSort.sort(inputArray);
-        Integer[] expectedOutput = {};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortSingleIntegerArray() {
-        Integer[] inputArray = {4};
-        Integer[] outputArray = simpleSort.sort(inputArray);
-        Integer[] expectedOutput = {4};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortSingleStringArray() {
-        String[] inputArray = {"s"};
-        String[] outputArray = simpleSort.sort(inputArray);
-        String[] expectedOutput = {"s"};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortNonDuplicateIntegerArray() {
-        Integer[] inputArray = {6, -1, 99, 27, -15, 23, -36};
-        Integer[] outputArray = simpleSort.sort(inputArray);
-        Integer[] expectedOutput = {-36, -15, -1, 6, 23, 27, 99};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortDuplicateIntegerArray() {
-        Integer[] inputArray = {6, -1, 27, -15, 23, 27, -36, 23};
-        Integer[] outputArray = simpleSort.sort(inputArray);
-        Integer[] expectedOutput = {-36, -15, -1, 6, 23, 23, 27, 27};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortNonDuplicateStringArray() {
-        String[] inputArray = {"s", "b", "k", "a", "d", "c", "h"};
-        String[] outputArray = simpleSort.sort(inputArray);
-        String[] expectedOutput = {"a", "b", "c", "d", "h", "k", "s"};
-        assertArrayEquals(outputArray, expectedOutput);
-    }
-
-    @Test
-    public void simpleSortDuplicateStringArray() {
-        String[] inputArray = {"s", "b", "d", "a", "d", "c", "h", "b"};
-        String[] outputArray = simpleSort.sort(inputArray);
-        String[] expectedOutput = {"a", "b", "b", "c", "d", "d", "h", "s"};
-        assertArrayEquals(outputArray, expectedOutput);
     }
 }