selection sort (#2177)

* selection sort

* Formatted with Google Java Formatter

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

Sorts/SelectionSort.java

@@ -1,68 +1,47 @@
 package Sorts;
 
-/**
- * @author Varun Upadhyay (https://github.com/varunu28)
- * @author Podshivalov Nikita (https://github.com/nikitap492)
- * @see SortAlgorithm
- */
 public class SelectionSort implements SortAlgorithm {
 
   /**
-   * This method swaps the two elements in the array
+   * Generic selection sort algorithm in increasing order.
    *
-   * @param <T>
-   * @param arr, i, j The array for the swap and the indexes of the to-swap elements
-   */
-  public <T> void swap(T[] arr, int i, int j) {
-    T temp = arr[i];
-    arr[i] = arr[j];
-    arr[j] = temp;
-  }
-
-  /**
-   * This method implements the Generic Selection Sort
-   *
-   * @param arr The array to be sorted Sorts the array in increasing order
+   * @param arr the array to be sorted.
+   * @param <T> the class of array.
+   * @return sorted array.
    */
   @Override
   public <T extends Comparable<T>> T[] sort(T[] arr) {
     int n = arr.length;
     for (int i = 0; i < n - 1; i++) {
-      // Initial index of min
-      int min = i;
-
+      int minIndex = i;
       for (int j = i + 1; j < n; j++) {
-        if (arr[min].compareTo(arr[j]) > 0) {
-          min = j;
+        if (arr[minIndex].compareTo(arr[j]) > 0) {
+          minIndex = j;
         }
       }
-
-      // Swapping if index of min is changed
-      if (min != i) {
-        swap(arr, i, min);
+      if (minIndex != i) {
+        T temp = arr[i];
+        arr[i] = arr[minIndex];
+        arr[minIndex] = temp;
       }
     }
-
     return arr;
   }
 
-  // Driver Program
+  /** Driver Code */
   public static void main(String[] args) {
 
     Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
-
     SelectionSort selectionSort = new SelectionSort();
-
     Integer[] sorted = selectionSort.sort(arr);
+    for (int i = 0; i < sorted.length - 1; ++i) {
+      assert sorted[i] <= sorted[i + 1];
+    }
 
-    // Output => 1	  4	 6	9	12	23	54	78	231
-    SortUtils.print(sorted);
-
-    // String Input
     String[] strings = {"c", "a", "e", "b", "d"};
     String[] sortedStrings = selectionSort.sort(strings);
-
-    // Output => a	b	 c  d	e
-    SortUtils.print(sortedStrings);
+    for (int i = 0; i < sortedStrings.length - 1; ++i) {
+      assert strings[i].compareTo(strings[i + 1]) <= 0;
+    }
   }
 }