From f1582867e131f3c79e75aaca470dc0ee89b3d438 Mon Sep 17 00:00:00 2001
From: PauLopNun <paulopeznunez@gmail.com>
Date: Mon, 6 Oct 2025 02:22:36 +0200
Subject: [PATCH 1/3] Add PostmanSort algorithm

- Implements Postman Sort using gap-based insertion approach
- Adaptive gap reduction with shrink factor of 1.3
- Includes comprehensive test suite extending SortingAlgorithmTest
---
 .../com/thealgorithms/sorts/PostmanSort.java  | 45 +++++++++++++++++++
 .../thealgorithms/sorts/PostmanSortTest.java  |  8 ++++
 2 files changed, 53 insertions(+)
 create mode 100644 src/main/java/com/thealgorithms/sorts/PostmanSort.java
 create mode 100644 src/test/java/com/thealgorithms/sorts/PostmanSortTest.java

diff --git a/src/main/java/com/thealgorithms/sorts/PostmanSort.java b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
new file mode 100644
index 000000000000..245b24dd4438
--- /dev/null
+++ b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
@@ -0,0 +1,45 @@
+package com.thealgorithms.sorts;
+
+import java.util.Arrays;
+
+/**
+ * Postman Sort Algorithm Implementation
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Postman_sort">Postman Sort Algorithm</a>
+ */
+public class PostmanSort implements SortAlgorithm {
+
+    @Override
+    public <T extends Comparable<T>> T[] sort(T[] array) {
+        if (array == null || array.length <= 1) {
+            return array;
+        }
+        postmanSort(array);
+        return array;
+    }
+
+    private <T extends Comparable<T>> void postmanSort(T[] array) {
+        int n = array.length;
+        double gapFactor = 1.3;
+        int gap = (int) (n / gapFactor);
+
+        while (gap > 0) {
+            for (int i = gap; i < n; i++) {
+                T temp = array[i];
+                int j = i;
+                while (j >= gap && SortUtils.greater(array[j - gap], temp)) {
+                    array[j] = array[j - gap];
+                    j -= gap;
+                }
+                array[j] = temp;
+            }
+            if (gap == 1) {
+                break;
+            }
+            gap = (int) (gap / gapFactor);
+            if (gap < 1) {
+                gap = 1;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java b/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java
new file mode 100644
index 000000000000..8d3cae41c057
--- /dev/null
+++ b/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java
@@ -0,0 +1,8 @@
+package com.thealgorithms.sorts;
+
+public class PostmanSortTest extends SortingAlgorithmTest {
+    @Override
+    SortAlgorithm getSortAlgorithm() {
+        return new PostmanSort();
+    }
+}
\ No newline at end of file

From c55606fbc86a27994cbd5abb2c2347b94f9817af Mon Sep 17 00:00:00 2001
From: PauLopNun <paulopeznunez@gmail.com>
Date: Mon, 6 Oct 2025 02:30:42 +0200
Subject: [PATCH 2/3] Fix clang-format: add newlines

---
 src/main/java/com/thealgorithms/sorts/PostmanSort.java     | 2 +-
 src/test/java/com/thealgorithms/sorts/PostmanSortTest.java | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/thealgorithms/sorts/PostmanSort.java b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
index 245b24dd4438..149dc6b6f393 100644
--- a/src/main/java/com/thealgorithms/sorts/PostmanSort.java
+++ b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
@@ -42,4 +42,4 @@ private <T extends Comparable<T>> void postmanSort(T[] array) {
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java b/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java
index 8d3cae41c057..0f8f349bfc02 100644
--- a/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java
+++ b/src/test/java/com/thealgorithms/sorts/PostmanSortTest.java
@@ -5,4 +5,4 @@ public class PostmanSortTest extends SortingAlgorithmTest {
     SortAlgorithm getSortAlgorithm() {
         return new PostmanSort();
     }
-}
\ No newline at end of file
+}

From 253735f368006e81a16a95831d626009ec71dcee Mon Sep 17 00:00:00 2001
From: PauLopNun <paulopeznunez@gmail.com>
Date: Mon, 6 Oct 2025 02:49:15 +0200
Subject: [PATCH 3/3] Remove unused import in PostmanSort

- Clean up unnecessary Arrays import
- Keep implementation focused and minimal
---
 src/main/java/com/thealgorithms/sorts/PostmanSort.java | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/main/java/com/thealgorithms/sorts/PostmanSort.java b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
index 149dc6b6f393..2226db222ef7 100644
--- a/src/main/java/com/thealgorithms/sorts/PostmanSort.java
+++ b/src/main/java/com/thealgorithms/sorts/PostmanSort.java
@@ -1,7 +1,5 @@
 package com.thealgorithms.sorts;
 
-import java.util.Arrays;
-
 /**
  * Postman Sort Algorithm Implementation
  *