From dd0003a478ab37c80e1e5ea7f706fe9a92e5338f Mon Sep 17 00:00:00 2001
From: cdjole <djordje.cvijetic@gmail.com>
Date: Tue, 23 Jul 2019 07:36:04 +0200
Subject: [PATCH] Shell sort (#7391)

* Shell sort

* Add new line at the end
---
 .../algorithms/shellsort/ShellSort.java       | 20 +++++++++++++++++++
 .../shellsort/ShellSortUnitTest.java          | 17 ++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java
 create mode 100644 algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java

diff --git a/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java b/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java
new file mode 100644
index 0000000000..c130e2d866
--- /dev/null
+++ b/algorithms-sorting/src/main/java/com/baeldung/algorithms/shellsort/ShellSort.java
@@ -0,0 +1,20 @@
+package com.baeldung.algorithms.shellsort;
+
+public class ShellSort {
+
+    public static void sort(int arrayToSort[]) {
+        int n = arrayToSort.length;
+
+        for (int gap = n / 2; gap > 0; gap /= 2) {
+            for (int i = gap; i < n; i++) {
+                int key = arrayToSort[i];
+                int j = i;
+                while (j >= gap && arrayToSort[j - gap] > key) {
+                    arrayToSort[j] = arrayToSort[j - gap];
+                    j -= gap;
+                }
+                arrayToSort[j] = key;
+            }
+        }
+    }
+}
diff --git a/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java b/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java
new file mode 100644
index 0000000000..91a27c41d0
--- /dev/null
+++ b/algorithms-sorting/src/test/java/com/baeldung/algorithms/shellsort/ShellSortUnitTest.java
@@ -0,0 +1,17 @@
+package com.baeldung.algorithms.shellsort;
+
+import static org.junit.Assert.*;
+import static org.junit.Assert.assertArrayEquals;
+
+import org.junit.Test;
+
+public class ShellSortUnitTest {
+
+    @Test
+    public void givenUnsortedArray_whenShellSort_thenSortedAsc() {
+        int[] input = {41, 15, 82, 5, 65, 19, 32, 43, 8};
+        ShellSort.sort(input);
+        int[] expected = {5, 8, 15, 19, 32, 41, 43, 65, 82};
+        assertArrayEquals("the two arrays are not equal", expected, input);
+    }
+}