Add SwapSort (#2520) (#2523)

Sorts/SwapSort.java

@@ -0,0 +1,67 @@
+package Sorts;
+
+import static Sorts.SortUtils.*;
+
+/**
+ * The idea of Swap-Sort is to count the number m of smaller values (that are in
+ * A) from each element of an array A(1...n) and then swap the element with the
+ * element in A(m+1). This ensures that the exchanged element is already in the
+ * correct, i.e. final, position. The disadvantage of this algorithm is that
+ * each element may only occur once, otherwise there is no termination.
+ */
+public class SwapSort implements SortAlgorithm {
+
+    @Override
+    public <T extends Comparable<T>> T[] sort(T[] array) {
+        int LENGTH = array.length;
+        int index = 0;
+
+        while (index < LENGTH - 1) {
+            int amountSmallerElements = this.getSmallerElementCount(array, index);
+
+            if (amountSmallerElements > 0 && index != amountSmallerElements) {
+                T element = array[index];
+                array[index] = array[amountSmallerElements];
+                array[amountSmallerElements] = element;
+            } else {
+                index++;
+            }
+        }
+
+        return array;
+    }
+
+    private <T extends Comparable<T>> int getSmallerElementCount(T[] array, int index) {
+        int counter = 0;
+        for (int i = 0; i < array.length; i++) {
+            if (less(array[i], array[index])) {
+                counter++;
+            }
+        }
+
+        return counter;
+    }
+
+    public static void main(String[] args) {
+        // ==== Int =======
+        Integer[] a = { 3, 7, 45, 1, 33, 5, 2, 9 };
+        System.out.print("unsorted: ");
+        print(a);
+        System.out.println();
+
+        new SwapSort().sort(a);
+        System.out.print("sorted: ");
+        print(a);
+        System.out.println();
+
+        // ==== String =======
+        String[] b = { "banana", "berry", "orange", "grape", "peach", "cherry", "apple", "pineapple" };
+        System.out.print("unsorted: ");
+        print(b);
+        System.out.println();
+
+        new SwapSort().sort(b);
+        System.out.print("sorted: ");
+        print(b);
+    }
+}