Added Shell Sort

Sorts/ShellSort.java

@@ -0,0 +1,68 @@
+package Sorts;
+
+/**
+ * @author dpunosevac
+ */
+public class ShellSort {
+
+  /**
+   * This method implements Generic Shell Sort.
+   * @param array The array to be sorted
+   */
+  public static void shellSort(Comparable[] array) {
+    int N = array.length;
+    int h = 1;
+
+    while (h < N/3) {
+      h = 3 * h + 1;
+    }
+
+    while (h >= 1) {
+      for (int i = h; i < N; i++) {
+        for (int j = i; j >= h && less(array[j], array[j-h]); j -= h) {
+          exch(array, j, j - h);
+        }
+      }
+
+      h /= 3;
+    }
+  }
+
+  /**
+   * Helper method for exchanging places in array
+   * @param array The array which elements we want to swap
+   * @param i index of the first element
+   * @param j index of the second element
+   */
+  private static void exch(Comparable[] array, int i, int j) {
+    Comparable swap = array[i];
+    array[i] = array[j];
+    array[j] = swap;
+  }
+
+  /**
+   * This method checks if first element is less then the other element
+   * @param v first element
+   * @param w second element
+   * @return true if the first element is less then the second element
+   */
+  private static boolean less(Comparable v, Comparable w) {
+    return v.compareTo(w) < 0;
+  }
+
+  public static void main(String[] args) {
+    // Integer Input
+    int[] arr1 = {4,23,6,78,1,54,231,9,12};
+    Integer[] array = new Integer[arr1.length];
+
+    for (int i=0;i<arr1.length;i++) {
+      array[i] = arr1[i];
+    }
+
+    shellSort(array);
+
+    for (int i = 0; i < array.length; i++) {
+      System.out.println(array[i]);
+    }
+  }
+}